Methods of and systems for processing using adjustable beam characteristics

ABSTRACT

A method of processing by controlling one or more beam characteristics of an optical beam may include: launching the optical beam into a first length of fiber having a first refractive-index profile (RIP); coupling the optical beam from the first length of fiber into a second length of fiber having a second RIP and one or more confinement regions; modifying the one or more beam characteristics of the optical beam in the first length of fiber, in the second length of fiber, or in the first and second lengths of fiber; confining the modified one or more beam characteristics of the optical beam within the one or more confinement regions of the second length of fiber; and/or generating an output beam, having the modified one or more beam characteristics of the optical beam, from the second length of fiber. The first RIP may differ from the second RIP.

RELATED APPLICATIONS

This application is a continuation-in-part of international applicationPCT/US2017/034848, filed May 26, 2017, which claims the benefit of U.S.Provisional Application No. 62/401,650, filed Sep. 29, 2016. Thisapplication is a continuation-in-part of U.S. patent application Ser.No. 15/607,411, filed May 26, 2017, which claims the benefit of U.S.Provisional Application No. 62/401,650, filed Sep. 29, 2016. Thisapplication is a continuation-in-part of U.S. patent application Ser.No. 15/607,410, filed May 26, 2017, which claims the benefit of U.S.Provisional Application No. 62/401,650, filed Sep. 29, 2016. Thisapplication is a continuation-in-part of U.S. patent application Ser.No. 15/607,399, filed May 26, 2017, which claims the benefit of U.S.Provisional Application No. 62/401,650, filed Sep. 29, 2016. All of theabove applications are herein incorporated by reference in theirentireties.

TECHNICAL FIELD

The subject matter disclosed herein generally relates to methods of andsystems for processing optical beams, such as laser beams associatedwith fiber-coupled lasers (e.g., disk lasers, diode lasers, fiberlasers, yttrium aluminum garnet (“YAG”) lasers). The subject matterdisclosed herein also relates to methods of and systems for processingusing adjustable beam characteristics, such as beam diameter, spot size,divergence profile, spatial profile, beam shape, or the like, or anycombination thereof, at an output, for example, of fiber-coupled lasers.

BACKGROUND

The use of high-power, fiber-coupled lasers continues to gain popularityfor a variety of applications, such as materials processing, cutting,welding, and/or additive manufacturing. These lasers include, forexample, fiber lasers, disk lasers, diode lasers, diode-pumped solidstate lasers, and lamp-pumped solid state lasers. In these systems,optical power is delivered from the laser to a work piece via an opticalfiber.

Various fiber-coupled laser materials processing tasks require differentbeam characteristics (e.g., spatial profiles and/or divergenceprofiles). For example, cutting thick metal and welding generallyrequire a larger beam diameter or spot size than cutting thin metal.Ideally, the laser beam properties would be adjustable to enableoptimized processing for these different tasks. Conventionally, usershave two choices: (1) employ a laser system with fixed beamcharacteristics that can be used for different tasks but is not optimalfor most of them (i.e., a compromise between performance andflexibility); or (2) purchase a laser system or accessories that offervariable beam characteristics but that add significant cost, size,weight, complexity, and perhaps performance degradation (e.g., opticalloss or reduced speed due to delays involved while varying beamcharacteristics) or reliability degradation (e.g., reduced robustness orup-time). Currently available laser systems capable of varying beamcharacteristics typically require the use of free-space optics or othercomplex and expensive add-on mechanisms (e.g., zoom lenses, mirrors,translatable or motorized lenses, combiners, etc.) in order to vary beamcharacteristics. No solution appears to exist which provides the desiredadjustability in beam characteristics that minimizes or eliminatesreliance on the use of free-space optics or other extra components thatadd significant penalties in terms of cost, complexity, performance,and/or reliability. What is needed is an in-fiber apparatus forproviding varying beam characteristics that does not require orminimizes the use of free-space optics and that can avoid significantcost, complexity, performance tradeoffs, and/or reliability degradation.

During additive manufacturing, standard laser beam shapes available oncommercial additive manufacturing (“AM”) systems typically are notoptimized for all the laser process capabilities that can be used duringAM. Nor do commercial AM systems generally provide the ability torapidly adjust laser beam properties during processing.

One of the factors determining the productivity of an additive system isthe build rate. The term “build rate” refers to the time required tofuse a unit volume of, for example, powder or wire. The higher the buildrate, the faster the productivity. However, higher build rates canproduce (1) coarser resolution of final products, (2) higher heat inputrequirements, (3) higher residual stresses in final products, (4)undesirable microstructures in final products, and/or (5) reductions inmechanical properties of final products. This trade-off in build rateand part quality helps to define the value of an AM tool. Typically,different parameters are used for areas of the build where differentbuild rates are required (for example contouring versus bulk filling, ordissimilar cladding versus similar deposition). The parameters that areadjusted are usually focus position, laser power, and/or speed. Theselimited variables produce limited process benefits.

There is an issue with doing these adjustments depending on what the X-Yposition is in the plane being created. For example, with powder bedfusion, a layer of powder may overlay what could be an existing fusedstructure or unfused powder, and control over the laser parameters asthe laser beam moves across these structures would provide a betterfinal part (less distortion, less porosity, better dimensionalaccuracy). This control also pertains to the finished part roughness, asthat is tied to the resolution used to create the edge of each layer.

Typically, standard commercial AM systems do not have the capability topre-heat a powder bed or a substrate above 400° C. This pre-heating isgenerally accomplished from the exterior of the build envelope (e.g.,using a heated platform or chamber). Thermal energy typically isgenerated electrically (resistive or inductive). The unfused powder isvery insulative. The shape and density of the structure being built canvary from build-to-build. The complications associated with thesefactors make it difficult to provide a uniform and repeatabletemperature in the build volume with such traditional heating methods.

At the same time, a laser source and associated beam delivery systemusually are developed for a single process: welding, cutting, cladding,drilling, marking, etc. As a result, an expensive laser AM tool may becapable of being used in only one process. The versatility and value ofsuch an AM tool may be severely limited by this single-processcapability.

SUMMARY

At least disclosed herein are methods of and systems for processingusing adjustable beam characteristics.

In some examples, a method of processing by controlling one or more beamcharacteristics of an optical beam can comprise: launching the opticalbeam into a first length of fiber having a first refractive-indexprofile (“RIP”); coupling the optical beam from the first length offiber into a second length of fiber having a second RIP and one or moreconfinement regions; modifying the one or more beam characteristics ofthe optical beam in the first length of fiber, in the second length offiber, or in the first and second lengths of fiber; confining themodified one or more beam characteristics of the optical beam within theone or more confinement regions of the second length of fiber; and/orgenerating an output beam, having the modified one or more beamcharacteristics of the optical beam, from the second length of fiber.The first RIP can differ from the second RIP.

In some examples, the method can further comprise: adjusting a BPP ofthe output beam for ablating, cladding, cutting, drilling, engraving,glazing, heat-treating, marking, patterning, roughening, smoothing,surface texturing, trepanning, and/or welding one or more parts of aproduct.

In some examples, the method can further comprise: adjusting a beamquality factor (M² factor) of the output beam for ablating, cladding,cutting, drilling, engraving, glazing, heat-treating, marking,patterning, roughening, smoothing, surface texturing, trepanning, and/orwelding one or more parts of a product.

In some examples, the method can further comprise: modulating the outputbeam while ablating, cladding, cutting, drilling, engraving, glazing,heat-treating, marking, patterning, roughening, smoothing, surfacetexturing, trepanning, and/or welding one or more parts of a product.The modulating of the output beam can occur, for example, during and/orafter manufacture of the product.

In some examples, the output beam can be generated as a series ofpulses, one or more characteristics of the output beam can be modifiedin a series of pulses, or the output beam can be generated as a seriesof pulses and one or more characteristics of the output beam can bemodified in a series of pulses.

In some examples, the output beam can be modulated at a selectedfrequency, one or more characteristics of the output beam can bemodulated at a selected frequency, or the output beam and one or morecharacteristics of the output beam can be modulated at a selectedfrequency.

In some examples, the output beam can be modulated at a selected dutycycle, one or more characteristics of the output beam can be modulatedat a selected duty cycle, or the output beam and one or morecharacteristics of the output beam can be modulated at a selected dutycycle.

In some examples, the method can further comprise: using the output beamfor ablating, cladding, cutting, drilling, engraving, glazing,heat-treating, marking, patterning, roughening, smoothing, surfacetexturing, trepanning, and/or welding one or more parts of a product.The using of the output beam can occur, for example, during and/or aftermanufacture of the product.

In some examples, the method can further comprise: increasing powerdensity of the output beam for ablating, cladding, cutting, drilling,engraving, glazing, marking, patterning, roughening, surface texturing,trepanning, and/or welding one or more parts of a product. Theincreasing of the power density can occur, for example, during and/orafter manufacture of the product.

In some examples, the method can further comprise: decreasing powerdensity of the output beam for cladding, cutting, engraving, glazing,heat-treating, marking, patterning, smoothing, surface texturing, and/ortrepanning one or more parts of a product. The decreasing of the powerdensity can occur, for example, during and/or after manufacture of theproduct.

In some examples, the method can further comprise: increasing beamdiameter of the output beam for heat-treating and/or smoothing one ormore parts of a product. The increasing of the beam diameter can occur,for example, during and/or after manufacture of the product.

In some examples, the method can further comprise: in additiveprocessing, alternately using the output beam to pre-heat powder priorto fusing the powder and using the output beam to fuse the powder.

In some examples, the method can further comprise: in additiveprocessing, alternately using the output beam to pre-heat powder priorto fusing the powder and using the output beam to post-heat the fusedpowder.

In some examples, the method can further comprise: in additiveprocessing, alternately using the output beam to fuse powder and usingthe output beam to post-heat the fused powder.

In some examples, the method can further comprise: in additiveprocessing, alternately using the output beam to pre-heat powder priorto fusing the powder, using the output beam to fuse the powder, andusing the output beam to post-heat the fused powder.

In some examples, the method can further comprise: in additiveprocessing, using a first portion of the output beam to pre-heat powderprior to fusing the powder, and simultaneously using a second portion ofthe output beam to fuse the powder.

In some examples, the method can further comprise: in additiveprocessing, using a first portion of the output beam to fuse powder, andsimultaneously using a second portion of the output beam to post-heatthe fused powder.

In some examples, the method can further comprise: in additiveprocessing, using a first portion of the output beam to pre-heat powderprior to fusing the powder, and simultaneously using the first portionof the output beam to post-heat the fused powder.

In some examples, the method can further comprise: in additiveprocessing, using a first portion of the output beam to pre-heat powderprior to fusing the powder, simultaneously using a second portion of theoutput beam to fuse the powder, and simultaneously using the firstportion of the output beam to post-heat the fused powder.

In some examples, a method of processing by controlling one or more beamcharacteristics of an optical beam can comprise: launching the opticalbeam into a first length of fiber having a first RIP; coupling theoptical beam from the first length of fiber into a second length offiber having a second RIP and two or more confinement regions; modifyingthe one or more beam characteristics of the optical beam in the firstlength of fiber, in the second length of fiber, or in the first andsecond lengths of fiber; confining the modified one or more beamcharacteristics of the optical beam within the two or more confinementregions of the second length of fiber; and/or generating an output beam,having the modified one or more beam characteristics of the opticalbeam, from the second length of fiber. The first RIP can be the same asthe second RIP.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory only,and are not restrictive of the present teachings, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects and advantages will become more apparentand more readily appreciated from the following detailed description ofexamples, taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates an example fiber structure for providing a laser beamhaving variable beam characteristics;

FIG. 2 depicts a cross-sectional view of an example fiber structure fordelivering a beam with variable beam characteristics;

FIG. 3 illustrates an example method of perturbing a fiber structure forproviding a beam having variable beam characteristics;

FIG. 4 is a graph illustrating the calculated spatial profile of thelowest-order mode (LP₀₁) for a first length of a fiber for differentfiber bend radii;

FIG. 5 illustrates an example of a two-dimensional intensitydistribution at a junction when a fiber for varying beam characteristicsis nearly straight;

FIG. 6 illustrates an example of a two-dimensional intensitydistribution at a junction when a fiber for varying beam characteristicsis bent with a radius chosen to preferentially excite a particularconfinement region of a second length of fiber;

FIGS. 7-10 depict experimental results to illustrate further outputbeams for various bend radii of a fiber for varying beam characteristicsshown in FIG. 2;

FIGS. 11-16 illustrate cross-sectional views of example first lengths offiber for enabling adjustment of beam characteristics in a fiberassembly;

FIGS. 17-19 illustrate cross-sectional views of example second lengthsof fiber (“confinement fibers”) for confining adjusted beamcharacteristics in a fiber assembly;

FIGS. 20 and 21 illustrate cross-sectional views of example secondlengths of fiber for changing a divergence angle of and confining anadjusted beam in a fiber assembly configured to provide variable beamcharacteristics;

FIG. 22A illustrates an example laser system including a fiber assemblyconfigured to provide variable beam characteristics disposed between afeeding fiber and process head;

FIG. 22B illustrates an example laser system including a fiber assemblyconfigured to provide variable beam characteristics disposed between afeeding fiber and process head;

FIG. 23 illustrates an example laser system including a fiber assemblyconfigured to provide variable beam characteristics disposed between afeeding fiber and multiple process fibers;

FIG. 24 illustrates examples of various perturbation assemblies forproviding variable beam characteristics according to various examplesprovided herein;

FIG. 25 illustrates an example process for adjusting and maintainingmodified characteristics of an optical beam;

FIGS. 26-28 are cross-sectional views illustrating example secondlengths of fiber (“confinement fibers”) for confining adjusted beamcharacteristics in a fiber assembly;

FIG. 29 depicts a first example method of processing by controlling oneor more beam characteristics of an optical beam;

FIG. 30 depicts a second example method of processing by controlling oneor more beam characteristics of an optical beam;

FIG. 31 depicts a plan view of a build layer having first and secondregions;

FIG. 32 depicts an elevation view of a 3D object manufactured using apowder bed process;

FIG. 33 depicts a plan view of a 3D object at a first point during thepowder bed process;

FIG. 34 depicts a plan view of a 3D object at a second point during thepowder bed process;

FIG. 35 depicts a plan view of a 3D object at a third point during thepowder bed process;

FIG. 36 depicts a plan view of a 3D object at a fourth point during thepowder bed process;

FIG. 37 depicts a plan view of a portion of a 3D object after fusing;

FIG. 38A depicts an elevation view of a 3D object after fusing; and

FIG. 38B depicts an elevation view of a 3D object after fusing andfurther processing.

DETAILED DESCRIPTION

Exemplary aspects will now be described more fully with reference to theaccompanying drawings. Examples of the disclosure, however, can beembodied in many different forms and should not be construed as beinglimited to the examples set forth herein. Rather, these examples areprovided so that this disclosure will be thorough and complete, and willfully convey the scope to one of ordinary skill in the art. In thedrawings, some details may be simplified and/or may be drawn tofacilitate understanding rather than to maintain strict structuralaccuracy, detail, and/or scale. For example, the thicknesses of layersand regions may be exaggerated for clarity.

It will be understood that when an element is referred to as being “on,”“connected to,” “electrically connected to,” or “coupled to” to anothercomponent, it may be directly on, connected to, electrically connectedto, or coupled to the other component or intervening components may bepresent. In contrast, when a component is referred to as being “directlyon,” “directly connected to,” “directly electrically connected to,” or“directly coupled to” another component, there are no interveningcomponents present. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that although the terms first, second, third,etc., may be used herein to describe various elements, components,regions, layers, and/or sections, these elements, components, regions,layers, and/or sections should not be limited by these terms. Theseterms are only used to distinguish one element, component, region,layer, and/or section from another element, component, region, layer,and/or section. For example, a first element, component, region, layer,or section could be termed a second element, component, region, layer,or section without departing from the teachings of examples.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper,” and the like may be used herein for ease of description todescribe the relationship of one component and/or feature to anothercomponent and/or feature, or other component(s) and/or feature(s), asillustrated in the drawings. It will be understood that the spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation(s) depicted inthe figures.

The terminology used herein is for the purpose of describing particularexamples only and is not intended to be limiting of examples. As usedherein, the singular forms “a,” “an,” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes,” and/or “including,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Although the operations of some of the disclosed methods are describedin a particular, sequential order for convenient presentation, it shouldbe understood that this manner of description encompasses rearrangement,unless a particular ordering is required by specific language set forthbelow. For example, operations described sequentially may in some casesbe rearranged or performed concurrently. Moreover, for the sake ofsimplicity, the attached figures may not show the various ways in whichthe disclosed systems, methods, and apparatuses can be used inconjunction with other systems, methods, and apparatuses. Additionally,the description sometimes uses terms like “produce” and “provide” todescribe the disclosed methods. These terms are high-level abstractionsof the actual operations that are performed. The actual operations thatcorrespond to these terms will vary depending on the particularimplementation and are readily discernible by a person of ordinary skillin the art.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as understood by one ofordinary skill in the art. It will be further understood that terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and should not be interpreted in anidealized or overly formal sense unless expressly so defined herein.

The present disclosure is directed to methods of and systems forprocessing using adjustable beam characteristics.

Definitions

Definitions of words and terms as used herein:

1. The term “beam characteristics” refers to one or more of thefollowing terms used to describe an optical beam. In general, the beamcharacteristics of most interest depend on the specifics of theapplication or optical system.

2. The term “beam diameter” is defined as the distance across the centerof the beam along an axis for which the irradiance (intensity) equals1/e² of the maximum irradiance (as understood by a person havingordinary skill in the art (“PHOSITA”)), other measures of beam diameterinclude, for example, full width at half maximum (“FWHM”) and secondmoment width/distance between 4σ values (“D4σ”)). While examplesdisclosed herein generally use beams that propagate in azimuthallysymmetric modes, elliptical or other beam shapes can be used, and beamdiameter can be different along different axes. Circular beams arecharacterized by a single beam diameter. Other beam shapes can havedifferent beam diameters along different axes.

3. The term “spot size” is the radial distance (radius) from the centerpoint of maximum irradiance to the 1/e² point (or equivalent for othermeasures of beam diameter—see definition of “beam diameter” above).

4. The term “beam divergence distribution” is the distribution ofenclosed power within a given propagation angle (e.g., full power vs.full cone angle). This quantity is sometimes called the “angulardistribution” or “NA distribution.”

5. The term “beam parameter product” (“BPP”) of a laser beam is definedas the product of the beam radius (measured at the beam waist) and thebeam divergence half-angle (measured in the far field). The units of BPPare typically millimeters-milliradians (“mm-mrad”).

6. A “confinement fiber” is defined to be a fiber that possesses one ormore confinement regions, wherein a confinement region comprises ahigher-index region (core region) surrounded by a lower-index region(cladding region). The RIP of a confinement fiber may include one ormore higher-index regions (core regions) surrounded by lower-indexregions (cladding regions), wherein light is guided in the higher-indexregions. Each confinement region and each cladding region can have anyRIP, including but not limited to step-index and graded-index. Theconfinement regions may or may not be concentric and may be a variety ofshapes such as circular, annular, polygonal, arcuate, elliptical,irregular, or the like, or any combination thereof. The confinementregions in a particular confinement fiber may all have the same shape ormay be different shapes. Moreover, confinement regions may be co-axialor may have offset axes with respect to one another. Confinement regionsmay be of uniform thickness about a central axis in the longitudinaldirection, or the thicknesses may vary about the central axis in thelongitudinal direction.

7. The term “intensity distribution” refers to optical intensity as afunction of position along a line (one-dimensional (“1D”) profile) or ona plane (two-dimensional (“2D”) profile). The line or plane is usuallytaken perpendicular to the propagation direction of the light. It is aquantitative property.

8. “Luminance” is a photometric measure of the luminous intensity perunit area of light travelling in a given direction.

9. “M² factor” (also called “beam quality factor” or “beam propagationfactor”) is a dimensionless parameter for quantifying the beam qualityof laser beams, with M²=1 being a diffraction-limited beam, and largervalues of the M² factor corresponding to lower beam quality. M² is equalto the BPP divided by λ/π, where λ is the wavelength of the beam inmicrons (if BPP is expressed in units of mm-mrad).

10. The term “numerical aperture” or “NA” of an optical system is adimensionless number that characterizes the range of angles over whichthe system can accept or emit light.

11. The term “optical intensity” is not an official (SI) unit, but isused to denote incident power per unit area on a surface or passingthrough a plane.

12. The term “power density” refers to optical power per unit area,although this is also referred to as “optical intensity.”

13. The term “radial beam position” refers to the position of a beam ina fiber measured with respect to the center of the fiber core in adirection perpendicular to the fiber axis.

14. “Radiance” is the radiation emitted per unit solid angle in a givendirection by a unit area of an optical source (e.g., a laser). Radiancemay be altered by changing the beam intensity distribution and/or beamdivergence profile or distribution. The ability to vary the radianceprofile of a laser beam implies the ability to vary the BPP.

15. The term “refractive-index profile” or “RIP” refers to therefractive index as a function of position along a line (1D) or in aplane (2D) perpendicular to the fiber axis. Many fibers are azimuthallysymmetric, in which case the 1D RIP is identical for any azimuthalangle.

16. A “step-index fiber” has a RIP that is flat (refractive indexindependent of position) within the fiber core.

17. A “graded-index fiber” has a RIP in which the refractive indexdecreases with increasing radial position (i.e., with increasingdistance from the center of the fiber core).

18. A “parabolic-index fiber” is a specific case of a graded-index fiberin which the refractive index decreases quadratically with increasingdistance from the center of the fiber core.

19. The term “additive manufacturing” refers to processes of joiningmaterials to make parts from three-dimensional (“3D”) model data,usually layer upon layer, as opposed to subtractive manufacturing andformative manufacturing methodologies. Powder bed fusion, for example,is one common additive material process.

20. The term “kerf width” refers to the width of material that isremoved during operations that remove material (e.g., cutting).

21. The term “build rate” refers to the time required to fuse a unitvolume of, for example, powder or wire.

22. The terms “fuse” and “fusing” refer to sintering, melting (e.g.,partially or fully melting), chemical bonding, or any other phenomena inwhich particles are joined together using heat (e.g., coalescing of twoor more materials due to application of heat).

Fiber for Varying Beam Characteristics

Disclosed herein are methods, systems, and apparatus configured toprovide a fiber operable to provide a laser beam having variable beamcharacteristics (“VBC”) that may reduce cost, complexity, optical loss,or other drawbacks of the conventional methods described above. This VBCfiber is configured to vary a wide variety of optical beamcharacteristics. Such beam characteristics can be controlled using theVBC fiber thus allowing users to tune various beam characteristics tosuit the particular requirements of an extensive variety of laserprocessing applications. For example, a VBC fiber may be used to tune:beam diameter, beam divergence distribution, BPP, intensitydistribution, M² factor, NA, optical intensity, power density, radialbeam position, radiance, spot size, or the like, or any combinationthereof.

In general, the disclosed technology entails coupling a laser beam intoa fiber in which the characteristics of the laser beam in the fiber canbe adjusted by perturbing the laser beam and/or perturbing a firstlength of fiber by any of a variety of methods (e.g., bending the fiberor introducing one or more other perturbations) and fully or partiallymaintaining adjusted beam characteristics in a second length of fiber.The second length of fiber is specially configured to maintain and/orfurther modify the adjusted beam characteristics. In some cases, thesecond length of fiber preserves the adjusted beam characteristicsthrough delivery of the laser beam to its ultimate use (e.g., materialsprocessing). The first and second lengths of fiber may comprise the sameor different fibers.

The disclosed technology is compatible with fiber-coupled lasers (e.g.,disk lasers, diode lasers, fiber lasers, YAG lasers). Fiber-coupledlasers typically deliver an output via a delivery fiber having astep-index refractive index profile (“RIP”), i.e., a flat or constantrefractive index within the fiber core. In reality, the RIP of thedelivery fiber may not be perfectly flat, depending on the design of thefiber. Important parameters are the fiber core diameter (“d_(core)”) andNA. The core diameter is typically in the range of 10-1000 microns(although other values are possible), and the NA is typically in therange of 0.06-0.22 (although other values are possible). A deliveryfiber from the laser may be routed directly to the process head or workpiece, or it may be routed to a fiber-to-fiber coupler (“FFC”) orfiber-to-fiber switch (“FFS”), which couples the light from the deliveryfiber into a process fiber that transmits the beam to the process heador the work piece.

Most materials processing tools, especially those at high power (>1kilowatt (“kW”)), employ multimode (“MM”) fiber, but some employsingle-mode (“SM”) fiber, which is at the lower end of the d_(core) andNA ranges. The beam characteristics from a SM fiber are uniquelydetermined by the fiber parameters. The beam characteristics from a MMfiber, however, can vary (unit-to-unit and/or as a function of laserpower and time), depending on the beam characteristics from the lasersource(s) coupled into the fiber, the launching or splicing conditionsinto the fiber, the fiber RIP, and the static and dynamic geometry ofthe fiber (bending, coiling, motion, micro-bending, etc.). For both SMand MM delivery fibers, the beam characteristics may not be optimum fora given materials processing task, and it is unlikely to be optimum fora range of tasks, motivating the desire to be able to systematicallyvary the beam characteristics in order to customize or optimize them fora particular processing task.

In one example, the VBC fiber may have a first length and a secondlength and may be configured to be interposed as an in-fiber devicebetween the delivery fiber and the process head to provide the desiredadjustability of the beam characteristics. To enable adjustment of thebeam, a perturbation device and/or assembly is disposed in closeproximity to and/or coupled with the VBC fiber and is responsible forperturbing the beam in a first length such that the beam'scharacteristics are altered in the first length of fiber, and thealtered characteristics are preserved or further altered as the beampropagates in the second length of fiber. The perturbed beam is launchedinto a second length of the VBC fiber configured to conserve adjustedbeam characteristics. The first and second lengths of fiber may be thesame or different fibers and/or the second length of fiber may comprisea confinement fiber. The beam characteristics that are conserved by thesecond length of VBC fiber may include any of: angular distribution,azimuthal intensity distribution, beam diameter, beam divergencedistribution, BPP, beam profile (e.g., Gaussian, flat-top), beam shape,divergence, divergence profile, intensity distribution, luminance, M²factor, NA, optical intensity profile, optical mode (e.g., filtering),power density profile, radial beam position, radiance, spatial profiledistribution, spot shape, spot size, or the like, or any combinationthereof.

FIG. 1 illustrates an example VBC fiber 100 for providing a laser beamhaving variable beam characteristics without requiring the use offree-space optics to change the beam characteristics. VBC fiber 100comprises a first length of fiber 104 and a second length of fiber 108.First length of fiber 104 and second length of fiber 108 may be the sameor different fibers and may have the same or different RIPs. The firstlength of fiber 104 and the second length of fiber 108 may be joinedtogether by a splice. First length of fiber 104 and second length offiber 108 may be coupled in other ways, may be spaced apart, or may beconnected via an interposing component such as another length of fiber,free-space optics, glue, index-matching material, or the like, or anycombination thereof.

A perturbation device 110 is disposed proximal to and/or envelopsperturbation region 106. Perturbation device 110 may be a device,assembly, in-fiber structure, and/or other feature. Perturbation device110 at least perturbs optical beam 102 in first length of fiber 104 orsecond length of fiber 108 or a combination thereof in order to adjustone or more beam characteristics of optical beam 102. Adjustment ofoptical beam 102 responsive to perturbation by perturbation device 110may occur in first length of fiber 104 or second length of fiber 108 ora combination thereof. Perturbation region 106 may extend over variouswidths and may or may not extend into a portion of second length offiber 108. As optical beam 102 propagates in VBC fiber 100, perturbationdevice 110 may physically act on VBC fiber 100 to perturb the fiber andadjust the characteristics of optical beam 102. Alternatively,perturbation device 110 may act directly on optical beam 102 to alterits beam characteristics. Subsequent to being adjusted, perturbed beam112 has different beam characteristics than optical beam 102, which willbe fully or partially conserved in second length of fiber 108. Inanother example, perturbation device 110 need not be disposed near asplice. Moreover, a splice may not be needed at all, for example VBCfiber 100 may be a single fiber, first length of fiber and second lengthof fiber could be spaced apart, or secured with a small gap (air-spacedor filled with an optical material, such as optical cement or anindex-matching material).

Perturbed beam 112 is launched into second length of fiber 108, whereperturbed beam 112 characteristics are largely maintained or continue toevolve as perturbed beam 112 propagates yielding the adjusted beamcharacteristics at the output of second length of fiber 108. In oneexample, the new beam characteristics may include an adjusted intensitydistribution. In an example, an altered beam intensity distribution willbe conserved in various structurally bounded confinement regions ofsecond length of fiber 108. Thus, the beam intensity distribution may betuned to a desired beam intensity distribution optimized for aparticular laser processing task. In general, the intensity distributionof perturbed beam 112 will evolve as it propagates in the second lengthof fiber 108 to fill the confinement region(s) into which perturbed beam112 is launched responsive to conditions in first length of fiber 104and perturbation caused by perturbation device 110. In addition, theangular distribution may evolve as the beam propagates in the secondfiber, depending on launch conditions and fiber characteristics. Ingeneral, fibers largely preserve the input divergence distribution, butthe distribution can be broadened if the input divergence distributionis narrow and/or if the fiber has irregularities or deliberate featuresthat perturb the divergence distribution. The various confinementregions, perturbations, and fiber features of second length of fiber 108are described in greater detail below. Optical beam 102 and perturbedbeam 112 are conceptual abstractions intended to illustrate how a beammay propagate through a VBC fiber 100 for providing variable beamcharacteristics and are not intended to closely model the behavior of aparticular optical beam.

VBC fiber 100 may be manufactured by a variety of methods includingPlasma Chemical Vapor Deposition (“PCVD”), Outside Vapor Deposition(“OVD”), Vapor Axial Deposition (“VAD”), Metal-Organic Chemical VaporDeposition (“MOCVD”), and/or Direct Nanoparticle Deposition (“DND”). VBCfiber 100 may comprise a variety of materials. For example, VBC fiber100 may comprise SiO₂, SiO₂ doped with GeO₂, germanosilicate, phosphoruspentoxide, phosphosilicate, Al₂O₃, aluminosilicate, or the like, or anycombination thereof. Confinement regions may be bounded by claddingdoped with fluorine, boron, or the like, or any combination thereof.Other dopants may be added to active fibers, including rare-earth ionssuch as Er³⁺ (erbium), Yb³⁺ (ytterbium), Nd³⁺ (neodymium), Tm³⁺(thulium), Ho³⁺ (holmium), or the like, or any combination thereof.Confinement regions may be bounded by cladding having a lower index thanthe confinement region with fluorine or boron doping. Alternatively, VBCfiber 100 may comprise photonic crystal fibers or micro-structuredfibers.

VBC fiber 100 is suitable for use in any of a variety of fiber, fiberoptic, or fiber laser devices, including continuous wave and pulsedfiber lasers, disk lasers, solid state lasers, or diode lasers (pulserate unlimited except by physical constraints). Furthermore,implementations in a planar waveguide or other types of waveguides andnot just fibers are within the scope of the claimed technology.

FIG. 2 depicts a cross-sectional view of an example VBC fiber 200 foradjusting beam characteristics of an optical beam. In an example, VBCfiber 200 may be a process fiber because it may deliver the beam to aprocess head for material processing. VBC fiber 200 comprises a firstlength of fiber 204 spliced at splice junction 206 to a second length offiber 208. A perturbation assembly 210 is disposed proximal to splicejunction 206. Perturbation assembly 210 may be any of a variety ofdevices configured to enable adjustment of the beam characteristics ofan optical beam 202 propagating in VBC fiber 200. In an example,perturbation assembly 210 may be a mandrel and/or another device thatmay provide means of varying the bend radius and/or bend length of VBCfiber 200 near the splice. Other examples of perturbation devices arediscussed below with respect to FIG. 24.

In an example, first length of fiber 204 has a parabolic-index first RIP212 as indicated by the left RIP graph. Most of the intensitydistribution of optical beam 202 is concentrated in the center of firstlength of fiber 204 when first length of fiber 204 is straight or nearlystraight. Second length of fiber 208 is a confinement fiber having asecond RIP 214 as shown in the right RIP graph. Second length of fiber208 includes confinement regions 216, 218, and 220. Confinement region216 is a central core surrounded by two annular (or ring-shaped)confinement regions 218 and 220. Layers 222 and 224 are structuralbarriers of lower index material between confinement regions 216, 218and/or 220, commonly referred to as “cladding” regions. In one example,layers 222 and 224 may comprise rings of fluorosilicate; in someembodiments, the fluorosilicate cladding layers are relatively thin.Other materials may be used as well and claimed subject matter is notlimited in this regard.

In an example, as optical beam 202 propagates along VBC fiber 200,perturbation assembly 210 may physically act on second length of fiber208 and/or optical beam 202 to adjust its beam characteristics andgenerate adjusted beam 226. In the current example, the intensitydistribution of optical beam 202 is modified by perturbation assembly210. Subsequent to adjustment of optical beam 202, the intensitydistribution of adjusted beam 226 may be concentrated in outerconfinement regions 218 and 220 with relatively little intensity in thecentral core confinement region 216. Because each of confinement regions216, 218, and/or 220 is isolated by the thin layers of lower indexmaterial in barrier layers 222 and 224, second length of fiber 208 cansubstantially maintain the adjusted intensity distribution of adjustedbeam 226. The beam will typically become distributed azimuthally withina given confinement region but will not transition (significantly)between the confinement regions as it propagates along the second lengthof fiber 208. Thus, the adjusted beam characteristics of adjusted beam226 are largely conserved within the isolated confinement regions 216,218, and/or 220. In some cases, it be may desirable to have the adjustedbeam 226 power divided among the confinement regions 216, 218, and/or220 rather than concentrated in a single region, and this condition maybe achieved by generating an appropriately adjusted beam 226.

In one example, central core confinement region 216 and annularconfinement regions 218 and 220 may be composed of fused silica glass,and cladding 222 and 224 defining the confinement regions may becomposed of fluorosilicate glass. Other materials may be used to formthe various confinement regions 216, 218, and/or 220, includinggermanosilicate, phosphosilicate, aluminosilicate, or the like, or acombination thereof, and claimed subject matter is not so limited. Othermaterials may be used to form the barrier rings 222 and/or 224,including fused silica, borosilicate, or the like, or a combinationthereof, and claimed subject matter is not so limited. In otherembodiments, the optical fibers or waveguides include or are composed ofvarious polymers, plastics, or crystalline materials. Generally, thecore confinement regions have refractive indices that are greater thanthe refractive indices of adjacent barrier/cladding regions.

In some examples, it may be desirable to increase a number ofconfinement regions in a second length of fiber to increase granularityof beam control over beam displacements for fine-tuning a beam profile.For example, confinement regions may be configured to provide stepwisebeam displacement.

FIG. 3 illustrates an example method of perturbing VBC fiber 200 forproviding variable beam characteristics of an optical beam. Changing thebend radius of a fiber may change the radial beam position, divergenceangle, and/or radiance profile of a beam within the fiber. The bendradius of VBC fiber 200 can be decreased from a first bend radius RI toa second bend radius R₂ about splice junction 206 by using a steppedmandrel or cone as the perturbation assembly 210. Additionally oralternatively, the engagement length on the mandrel(s) or cone can bevaried. Rollers 250 may be employed to engage VBC fiber 200 acrossperturbation assembly 210. In an example, an amount of engagement ofrollers 250 with VBC fiber 200 has been shown to shift the distributionof the intensity profile to the outer confinement regions 218 and 220 ofVBC fiber 200 with a fixed mandrel radius. There are a variety of othermethods for varying the bend radius of VBC fiber 200, such as using aclamping assembly, flexible tubing, or the like, or a combinationthereof, and claimed subject matter is not limited in this regard. Inanother example, for a particular bend radius the length over which VBCfiber 200 is bent can also vary beam characteristics in a controlled andreproducible way. In examples, changing the bend radius and/or lengthover which the fiber is bent at a particular bend radius also modifiesthe intensity distribution of the beam such that one or more modes maybe shifted radially away from the center of a fiber core.

Maintaining the bend radius of the fibers across splice junction 206ensures that the adjusted beam characteristics such as radial beamposition and radiance profile of optical beam 202 will not return tooptical beam 202's unperturbed state before being launched into secondlength of fiber 208. Moreover, the adjusted radial beam characteristics,including position, divergence angle, and/or intensity distribution, ofadjusted beam 226 can be varied based on an extent of decrease in thebend radius and/or the extent of the bend length of VBC fiber 200. Thus,specific beam characteristics may be obtained using this method.

In the current example, first length of fiber 204 having first RIP 212is spliced at splice junction 206 to a second length of fiber 208 havingthe second RIP 214. However, it is possible to use a single fiber havinga single RIP formed to enable perturbation (e.g., by micro-bending) ofthe beam characteristics of optical beam 202 and also to enableconservation of the adjusted beam. Such a RIP may be similar to the RIPsshown in fibers illustrated in FIGS. 17, 18, and/or 19.

FIGS. 7-10 provide experimental results for VBC fiber 200 (shown inFIGS. 2 and 3) and illustrate further a beam response to perturbation ofVBC fiber 200 when a perturbation assembly 210 acts on VBC fiber 200 tobend the fiber. FIGS. 4-6 are simulations and FIGS. 7-10 areexperimental results wherein a beam from a SM 1050 nanometer (“nm”)source was launched into an input fiber (not shown) with a 40 micron(“μm”) core diameter. The input fiber was spliced to first length offiber 204.

FIG. 4 is an example graph 400 illustrating the calculated profile ofthe lowest-order mode (LP₀₁) for a first length of fiber 204 fordifferent fiber bend radii 402, wherein a perturbation assembly 210involves bending VBC fiber 200. As the fiber bend radius is decreased,an optical beam propagating in VBC fiber 200 is adjusted such that themode shifts radially away from the center 404 of a VBC fiber 200 core(r=0 micron or μm) toward the core/cladding interface (located at r=100microns in this example). Higher-order modes (LR_(In)) also shift withbending. Thus, a straight or nearly straight fiber (very large bendradius), curve 406 for LP₀₁ is centered at or near the center of VBCfiber 200. At a bend radius of about 6 centimeters (“cm”), curve 408 forLP₀₁ is shifted to a radial position of about 40 μm from the center 404of VBC fiber 200. At a bend radius of about 5 cm, curve 410 for LP₀₁ isshifted to a radial position about 50 μm from the center 404 of VBCfiber 200. At a bend radius of about 4 cm, curve 412 for LP₀₁ is shiftedto a radial position about 60 μm from the center 404 of VBC fiber 200.At a bend radius of about 3 cm, curve 414 for LP₀₁ is shifted to aradial position about 80 μm from the center 404 of VBC fiber 200. At abend radius of about 2.5 cm, a curve 416 for LP₀₁ is shifted to a radialposition about 85 μm from the center 404 of VBC fiber 200. Note that theshape of the mode remains relatively constant (until it approaches theedge of the core), which is a specific property of a parabolic RIP.Although, this property may be desirable in some situations, it is notrequired for the VBC functionality, and other RIPs may be employed.

In an example, if VBC fiber 200 is straightened, LP₀₁ mode will shiftback toward the center of the fiber. Thus, the purpose of second lengthof fiber 208 is to “trap” or confine the adjusted intensity distributionof the beam in a confinement region that is displaced from the center ofthe VBC fiber 200. The splice between first length of fiber 204 andsecond length of fiber 208 is included in the bent region, thus theshifted mode profile will be preferentially launched into one of thering-shaped confinement regions 218 and 220 or be distributed among theconfinement regions. FIGS. 5 and 6 illustrate this effect.

FIG. 5 illustrates an example two-dimensional intensity distribution atsplice junction 206 within second length of fiber 208 when VBC fiber 200is nearly straight. A significant portion of LP₀₁ and LP_(In) are withinconfinement region 216 of second length of fiber 208. FIG. 6 illustratesthe two-dimensional intensity distribution at splice junction 206 withinsecond length of fiber 208 when VBC fiber 200 is bent with a radiuschosen to preferentially excite confinement region 220 (the outermostconfinement region) of second length of fiber 208. A significant portionof LP₀₁ and LP_(In) are within confinement region 220 of second lengthof fiber 208.

In an example, second length of fiber 208 confinement region 216 has a100 micron diameter, confinement region 218 is between 120 micron and200 micron in diameter, and confinement region 220 is between 220 micronand 300 micron diameter. Confinement regions 216, 218, and 220 areseparated by 10 um thick rings of fluorosilicate, providing an NA of0.22 for the confinement regions. Other inner and outer diameters forthe confinement regions, thicknesses of the rings separating theconfinement regions, NA values for the confinement regions, and numbersof confinement regions may be employed.

Referring again to FIG. 5, with the noted parameters, when VBC fiber 200is straight about 90% of the power is contained within the centralconfinement region 216, and about 100% of the power is contained withinconfinement regions 216 and 218. Referring now to FIG. 6, when VBC fiber200 is bent to preferentially excite second ring confinement region 220,nearly 75% of the power is contained within confinement region 220, andmore than 95% of the power is contained within confinement regions 218and 220. These calculations include LP₀₁, and two higher-order modes,which is typical in some 2-4 kW fiber lasers.

It is clear from FIGS. 5 and 6 that in the case where a perturbationassembly 210 acts on VBC fiber 200 to bend the fiber, the bend radiusdetermines the spatial overlap of the modal intensity distribution ofthe first length of fiber 204 with the different guiding confinementregions 216, 218, and/or 220 of the second length of fiber 208. Changingthe bend radius can thus change the intensity distribution at the outputof the second length of fiber 208, thereby changing the beam diameter orspot size of the beam, and thus also changing its radiance and BPPvalue. This adjustment of the beam diameter or spot size may beaccomplished in an all-fiber structure, involving no free-space opticsand consequently may reduce or eliminate the disadvantages of free-spaceoptics discussed above. Such adjustments can also be made with otherperturbation assemblies that alter bend radius, bend length, fibertension, temperature, or other perturbations discussed below.

In a typical materials processing system (e.g., a cutting or weldingtool), the output of the process fiber is imaged at or near the workpiece by the process head. Varying the intensity distribution as shownin FIGS. 5 and 6 thus enables variation of the beam profile at the workpiece in order to tune and/or optimize the process, as desired. SpecificRIPs for the two fibers were assumed for the purpose of the abovecalculations, but other RIPs are possible, and claimed subject matter isnot limited in this regard.

FIGS. 7-10 depict experimental results (measured intensitydistributions) to illustrate further output beams for various bend radiiof VBC fiber 200 shown in FIG. 2.

In FIG. 7 when VBC fiber 200 is straight, the beam is nearly completelyconfined to confinement region 216. As the bend radius is decreased, theintensity distribution shifts to higher diameters (FIGS. 8-10). FIG. 8depicts the intensity distribution when the bend radius of VBC fiber 200is chosen to shift the intensity distribution preferentially toconfinement region 218. FIG. 9 depicts the experimental results when thebend radius is further reduced and chosen to shift the intensitydistribution outward to confinement region 220 and confinement region218. In FIG. 10, at the smallest bend radius, the beam is nearly a“donut mode,” with most of the intensity in the outermost confinementregion 220.

Despite excitation of the confinement regions from one side at thesplice junction 206, the intensity distributions are nearly symmetricazimuthally because of scrambling within confinement regions as the beampropagates within the VBC fiber 200. Although the beam will typicallyscramble azimuthally as it propagates, various structures orperturbations (e.g., coils) could be included to facilitate thisprocess.

For the fiber parameters used in the experiment shown in FIGS. 7-10,particular confinement regions were not exclusively excited because someintensity was present in multiple confinement regions. This feature mayenable advantageous materials processing applications that are optimizedby having a flatter or distributed beam intensity distribution. Inapplications requiring cleaner excitation of a given confinement region,different fiber RIPs could be employed to enable this feature.

The results shown in FIGS. 7-10 pertain to the particular fibers used inthis experiment, and the details will vary depending on the specifics ofthe implementation. In particular, the spatial profile and divergencedistribution of the output beam and their dependence on bend radius willdepend on the specific RIPs employed, on the splice parameters, and onthe characteristics of the laser source launched into the first fiber.

Different fiber parameters than those shown in FIG. 2 may be used andstill be within the scope of the claimed subject matter. Specifically,different RIPs and core sizes and shapes may be used to facilitatecompatibility with different input beam profiles and to enable differentoutput beam characteristics. Example RIPs for the first length of fiber,in addition to the parabolic-index profile shown in FIG. 2, includeother graded-index profiles, step-index, pedestal designs (i.e., nestedcores with progressively lower refractive indices with increasingdistance from the center of the fiber), and designs with nested coreswith the same refractive index value but with various NA values for thecentral core and the surrounding rings. Example RIPs for the secondlength of fiber, in addition to the profile shown in FIG. 2, includeconfinement fibers with different numbers of confinement regions,non-uniform confinement-region thicknesses, different and/or non-uniformvalues for the thicknesses of the rings surrounding the confinementregions, different and/or non-uniform NA values for the confinementregions, different refractive-index values for the high-index andlow-index portions of the RIP, non-circular confinement regions (such aselliptical, oval, polygonal, square, rectangular, or combinationsthereof), as well as other designs as discussed in further detail withrespect to FIGS. 26-28. Furthermore, VBC fiber 200 and other examples ofa VBC fiber described herein are not restricted to use of two fibers. Insome examples, implementation may include use of one fiber or more thantwo fibers. In some cases, the fiber(s) may not be axially uniform; forexample, they could include fiber Bragg gratings or long-periodgratings, or the diameter could vary along the length of the fiber. Inaddition, the fibers do not have to be azimuthally symmetric (e.g., thecore(s) could have square or polygonal shapes). Various fiber coatings(buffers) may be employed, including high-index or index-matchedcoatings (which strip light at the glass-polymer interface) andlow-index coatings (which guide light by total internal reflection atthe glass-polymer interface). In some examples, multiple fiber coatingsmay be used on VBC fiber 200.

FIGS. 11-16 illustrate cross-sectional views of examples of firstlengths of fiber for enabling adjustment of beam characteristics in aVBC fiber responsive to perturbation of an optical beam propagating inthe first lengths of fiber. Some examples of beam characteristics thatmay be adjusted in the first length of fiber are: angular distribution,azimuthal intensity distribution, beam diameter, beam divergencedistribution, BPP, beam profile (e.g., Gaussian, flat-top), beam shape,divergence, divergence profile, intensity distribution, luminance, M²factor, NA, optical intensity profile, optical mode (e.g., filtering),power density profile, radial beam position, radiance, spatial profiledistribution, spot shape, spot size, or the like, or any combinationthereof. The first lengths of fiber depicted in FIGS. 11-16 anddescribed below are merely examples and do not provide an exhaustiverecitation of the variety of first lengths of fiber that may be utilizedto enable adjustment of beam characteristics in a VBC fiber assembly.Selection of materials, appropriate RIPs, and other variables for thefirst lengths of fiber illustrated in FIGS. 11-16 at least depend on adesired beam output. A wide variety of fiber variables are contemplatedand are within the scope of the claimed subject matter. Thus, claimedsubject matter is not limited by examples provided herein.

In FIG. 11 first length of fiber 1100 comprises a step-index profile1102. FIG. 12 illustrates a first length of fiber 1200 comprising a“pedestal RIP” (i.e., a core comprising a step-index region surroundedby a larger step-index region) 1202. FIG. 13 illustrates first length offiber 1300 comprising a multiple-pedestal RIP 1302.

FIG. 14A illustrates first length of fiber 1400 comprising agraded-index profile 1418 surrounded by a down-doped region 1404. Whenfirst length of fiber 1400 is perturbed, modes may shift radiallyoutward in first length of fiber 1400 (e.g., during bending of firstlength of fiber 1400). Graded-index profile 1402 may be designed topromote maintenance or even compression of modal shape. This design maypromote adjustment of a beam propagating in first length of fiber 1400to generate a beam having a beam intensity distribution concentrated inan outer perimeter of the fiber (i.e., in a portion of the fiber corethat is displaced from the fiber axis). As described above, when theadjusted beam is coupled into a second length of fiber havingconfinement regions, the intensity distribution of the adjusted beam maybe trapped in the outermost confinement region, providing a donut shapedintensity distribution. A beam spot having a narrow outer confinementregion may be useful to enable certain material processing actions.

FIG. 14B illustrates first length of fiber 1406 comprising agraded-index profile 1414 surrounded by a down-doped region 1408 similarto first length of fiber 1400. However, first length of fiber 1406includes a divergence structure 1410 (a lower-index region) as can beseen in profile 1412. The divergence structure 1410 is an area ofmaterial with a lower refractive index than that of the surroundingcore. As the beam is launched into first length of fiber 1406,refraction from divergence structure 1410 causes the beam divergence toincrease in first length of fiber 1406. The amount of increaseddivergence depends on the amount of spatial overlap of the beam with thedivergence structure 1410 and the magnitude of the index differencebetween the divergence structure 1410 and the core material. Divergencestructure 1410 can have a variety of shapes, depending on the inputdivergence distribution and desired output divergence distribution. Inan example, divergence structure 1410 has a triangular or graded indexshape.

FIG. 15 illustrates a first length of fiber 1500 comprising aparabolic-index central region 1508 surrounded by a constant-indexregion 1502, and the constant-index region 1502 is surrounded by alower-index annular layer 1506 and another constant-index region 1504.The lower-index annular layer 1506 helps guide a beam propagating infirst length of fiber 1500. When the propagating beam is perturbed,modes shift radially outward in first length of fiber 1500 (e.g., duringbending of first length of fiber 1500). As one or more modes shiftradially outward, parabolic-index central region 1508 promotes retentionof modal shape. When the modes reach the constant-index region of theRIP 1510, they will be compressed against the lower-index annular layer1506, which may cause preferential excitation of the outermostconfinement region in the second fiber (in comparison to the first fiberRIP shown in FIG. 14). In one implementation, this fiber design workswith a confinement fiber having a central step-index core and a singleannular core. The parabolic-index central region 1508 of the RIPoverlaps with the central step-index core of the confinement fiber. Theconstant-index region 1502 overlaps with the annular core of theconfinement fiber. The constant-index region 1502 of the first fiber isintended to make it easier to move the beam into overlap with theannular core by bending. This fiber design also works with other designsof the confinement fiber.

FIG. 16 illustrates a first length of fiber 1600, having RIP 1602,comprising guiding regions 1604, 1606, 1608, and 1616 bounded bylower-index layers 1610, 1612, and 1614 where the indexes of thelower-index layers 1610, 1612, and 1614 are stepped or, more generally,do not all have the same value. The stepped-index layers may serve tobound the beam intensity to certain guiding regions 1604, 1606, 1608,and/or 1616 when the perturbation assembly 210 (see FIG. 2) acts on thefirst length of fiber 1600. In this way, adjusted beam light may betrapped in the guiding regions over a range of perturbation actions(such as over a range of bend radii, a range of bend lengths, a range ofmicro-bending pressures, and/or a range of acousto-optical signals),allowing for a certain degree of perturbation tolerance before a beamintensity distribution is shifted to a more distant radial position infirst length of fiber 1600. Thus, variation in beam characteristics maybe controlled in a step-wise fashion. The radial widths of the guidingregions 1604, 1606, 1608, and 1616 may be adjusted to achieve a desiredring width, as may be required by an application. Also, a guiding regioncan have a thicker radial width to facilitate trapping of a largerfraction of the incoming beam profile if desired. Guiding region 1606 isan example of such a design.

FIGS. 17-21 depict examples of fibers configured to enable maintenanceand/or confinement of adjusted beam characteristics in the second lengthof fiber (e.g., second length of fiber 208). These fiber designs arereferred to as “ring-shaped confinement fibers” because they contain acentral core surrounded by annular or ring-shaped cores. These designsare merely examples and not an exhaustive recitation of the variety offiber RIPs that may be used to enable maintenance and/or confinement ofadjusted beam characteristics within a fiber. Thus, claimed subjectmatter is not limited to the examples provided herein. Moreover, any ofthe first lengths of fiber described above with respect to FIGS. 11-16may be combined with any of the second length of fiber described FIGS.17-21.

FIG. 17 illustrates a cross-sectional view of an example second lengthof fiber for maintaining and/or confining adjusted beam characteristicsin a VBC fiber assembly. As the perturbed beam is coupled from a firstlength of fiber to second length of fiber 1700, the second length offiber 1700 may maintain at least a portion of the beam characteristicsadjusted in response to perturbation in the first length of fiber withinone or more of confinement regions 1704, 1706, and/or 1708. Secondlength of fiber 1700 has a RIP 1702. Each of confinement regions 1704,1706, and/or 1708 is bounded by a lower index layer 1710 and/or 1712.This design enables second length of fiber 1700 to maintain the adjustedbeam characteristics. As a result, a beam output by second length offiber 1700 will substantially maintain the received adjusted beam asmodified in the first length of fiber giving the output beam adjustedbeam characteristics, which may be customized to a processing task orother application.

Similarly, FIG. 18 depicts a cross-sectional view of an example secondlength of fiber 1800 for maintaining and/or confining beamcharacteristics adjusted in response to perturbation in the first lengthof fiber in a VBC fiber assembly. Second length of fiber 1800 has a RIP1802. However, confinement regions 1808, 1810, and/or 1812 havedifferent thicknesses than confinement regions 1704, 1706, and 1708.Each of confinement regions 1808, 1810, and/or 1812 is bounded by alower index layer 1804 and/or 1806. Varying the thicknesses of theconfinement regions (and/or barrier regions) enables tailoring oroptimization of a confined adjusted radiance profile by selectingparticular radial positions within which to confine an adjusted beam.

FIG. 19 depicts a cross-sectional view of an example second length offiber 1900 having a RIP 1902 for maintaining and/or confining anadjusted beam in a VBC fiber assembly configured to provide variablebeam characteristics. In this example, the number and thicknesses ofconfinement regions 1904, 1906, 1908, and 1910 are different from secondlengths of fiber 1700 and 1800 and the barrier layers 1912, 1914, and1916 are of varied thicknesses as well. Furthermore, confinement regions1904, 1906, 1908, and 1910 have different indexes of refraction andbarrier layers 1912, 1914, and 1916 have different indexes of refractionas well. This design may further enable a more granular or optimizedtailoring of the confinement and/or maintenance of an adjusted beamradiance to particular radial locations within second length of fiber1900. As the perturbed beam is launched from a first length of fiber tosecond length of fiber 1900 the modified beam characteristics of thebeam (having an adjusted intensity distribution, radial position, and/ordivergence angle, or the like, or a combination thereof) is confinedwithin a specific radius by one or more of confinement regions 1904,1906, 1908, and/or 1910 of second length of fiber 1900.

As noted previously, the divergence angle of a beam may be conserved oradjusted and then conserved in the second length of fiber. There are avariety of methods to change the divergence angle of a beam. Thefollowing are examples of fibers configured to enable adjustment of thedivergence angle of a beam propagating from a first length of fiber to asecond length of fiber in a fiber assembly for varying beamcharacteristics. However, these are merely examples and not anexhaustive recitation of the variety of methods that may be used toenable adjustment of divergence of a beam. Thus, claimed subject matteris not limited to the examples provided herein.

FIG. 20 depicts a cross-sectional view of an example second length offiber 2000 having RIP 2002 for modifying, maintaining, and/or confiningbeam characteristics adjusted in response to perturbation in the firstlength of fiber. In this example, second length of fiber 2000 is similarto the previously described second lengths of fiber and forms a portionof the VBC fiber assembly for delivering variable beam characteristicsas discussed above. There are three confinement regions 2004, 2006, and2008 and three barrier layers 2010, 2012, and 2016. Second length offiber 2000 also has a divergence structure 2014 situated within theconfinement region 2006. The divergence structure 2014 is an area ofmaterial with a lower refractive index than that of the surroundingconfinement region. As the beam is launched into second length of fiber2000, refraction from divergence structure 2014 causes the beamdivergence to increase in second length of fiber 2000. The amount ofincreased divergence depends on the amount of spatial overlap of thebeam with the divergence structure 2014 and the magnitude of the indexdifference between the divergence structure 2014 and the core material.By adjusting the radial position of the beam near the launch point intothe second length of fiber 2000, the divergence distribution may bevaried, The adjusted divergence of the beam is conserved in secondlength of fiber 2000, which is configured to deliver the adjusted beamto the process head, another optical system (e.g., fiber-to-fibercoupler or fiber-to-fiber switch), the work piece, or the like, or anycombination thereof. In an example, divergence structure 2014 may havean index dip of about 10⁻⁵3×10⁻² with respect to the surroundingmaterial. Other values of the index dip may be employed within the scopeof this disclosure and claimed subject matter is not so limited.

FIG. 21 depicts a cross-sectional view of an example second length offiber 2100 having a RIP 2102 for modifying, maintaining, and/orconfining beam characteristics adjusted in response to perturbation inthe first length of fiber. Second length of fiber 2100 forms a portionof a VBC fiber assembly for delivering a beam having variablecharacteristics. In this example, there are three confinement regions2104, 2106, and 2108 and three barrier layers 2110, 2112, and 2116.Second length of fiber 2100 also has a plurality of divergencestructures 2114 and 2118. The divergence structures 2114 and 2118 areareas of graded lower index material. As the beam is launched from thefirst length fiber into second length of fiber 2100, refraction fromdivergence structures 2114 and 2118 causes the beam divergence toincrease. The amount of increased divergence depends on the amount ofspatial overlap of the beam with the divergence structure and themagnitude of the index difference between the divergence structure 2114and/or 2118 and the surrounding core material of confinement regions2106 and 2104 respectively. By adjusting the radial position of the beamnear the launch point into the second length of fiber 2100, thedivergence distribution may be varied. The design shown in FIG. 21allows the intensity distribution and the divergence distribution to bevaried somewhat independently by selecting both a particular confinementregion and the divergence distribution within that conferment region(because each confinement region may include a divergence structure).The adjusted divergence of the beam is conserved in second length offiber 2100, which is configured to deliver the adjusted beam to theprocess head, another optical system, or the work piece. Forming thedivergence structures 2114 and 2118 with a graded or non-constant indexenables tuning of the divergence profile of the beam propagating insecond length of fiber 2100. An adjusted beam characteristic such as aradiance profile and/or divergence profile may be conserved as it isdelivered to a process head by the second fiber. Alternatively, anadjusted beam characteristic such as a radiance profile and/ordivergence profile may be conserved or further adjusted as it is routedby the second fiber through a fiber-to-fiber coupler (“FFC”) and/orfiber-to-fiber switch (“FFS”) and to a process fiber, which delivers thebeam to the process head or the work piece.

FIGS. 26-28 are cross-sectional views illustrating examples of fibersand fiber RIPs configured to enable maintenance and/or confinement ofadjusted beam characteristics of a beam propagating in an azimuthallyasymmetric second length of fiber wherein the beam characteristics areadjusted responsive to perturbation of a first length of fiber coupledto the second length of fiber and/or perturbation of the beam by aperturbation device 110. These azimuthally asymmetric designs are merelyexamples and are not an exhaustive recitation of the variety of fiberRIPs that may be used to enable maintenance and/or confinement ofadjusted beam characteristics within an azimuthally asymmetric fiber.Thus, claimed subject matter is not limited to the examples providedherein. Moreover, any of a variety of first lengths of fiber (e.g., likethose described above) may be combined with any azimuthally asymmetricsecond length of fiber (e.g., like those described in FIGS. 26-28).

FIG. 26 illustrates RIPs at various azimuthal angles of a cross-sectionthrough an elliptical fiber 2600. At a first azimuthal angle 2602,elliptical fiber 2600 has a first RIP 2604. At a second azimuthal angle2606 that is rotated 45° from first azimuthal angle 2602, ellipticalfiber 2600 has a second RIP 2608. At a third azimuthal angle 2610 thatis rotated another 45° from second azimuthal angle 2606, ellipticalfiber 2600 has a third RIP 2612. First, second, and third RIPs 2604,2608, and 2612 are all different.

FIG. 27 illustrates RIPs at various azimuthal angles of a cross-sectionthrough a multicore fiber 2700. At a first azimuthal angle 2702,multicore fiber 2700 has a first RIP 2704. At a second azimuthal angle2706, multicore fiber 2700 has a second RIP 2708. First and second RIPs2704 and 2708 are different. In an example, perturbation device 110 mayact in multiple planes in order to launch the adjusted beam intodifferent regions of an azimuthally asymmetric second fiber.

FIG. 28 illustrates RIPs at various azimuthal angles of a cross-sectionthrough a fiber 2800 having at least one crescent shaped core. In somecases, the corners of the crescent may be rounded, flattened, orotherwise shaped, which may minimize optical loss. At a first azimuthalangle 2802, fiber 2800 has a first RIP 2804. At a second azimuthal angle2806, fiber 2800 has a second RIP 2808. First and second RIPs 2804 and2808 are different.

FIG. 22A illustrates an example of a laser system 2200 including a VBCfiber assembly 2202 configured to provide variable beam characteristics.VBC fiber assembly 2202 comprises a first length of fiber 104, secondlength of fiber 108, and a perturbation device 110. VBC fiber assembly2202 is disposed between feeding fiber 2212 (i.e., the output fiber fromthe laser source) and VBC delivery fiber 2240. VBC delivery fiber 2240may comprise second length of fiber 108 or an extension of second lengthof fiber 108 that modifies, maintains, and/or confines adjusted beamcharacteristics. Beam 2210 is coupled into VBC fiber assembly 2202 viafeeding fiber 2212. VBC Fiber assembly 2202 is configured to vary thecharacteristics of beam 2210 in accordance with the various examplesdescribed above. The output of VBC fiber assembly 2202 is adjusted beam2214 which is coupled into VBC delivery fiber 2240. VBC delivery fiber2240 delivers adjusted beam 2214 to free-space optics assembly 2208,which then couples adjusted beam 2214 into a process fiber 2204.Adjusted beam 2214 is then delivered to process head 2206 by processfiber 2204. The process head can include guided wave optics (such asfibers and fiber coupler), free space optics such as lenses, mirrors,optical filters, diffraction gratings), beam scan assemblies such asgalvanometer scanners, polygonal mirror scanners, or other scanningsystems that are used to shape the adjusted beam 2214 and deliver theshaped beam to a workpiece.

In laser system 2200, one or more of the free-space optics of free-spaceoptics assembly 2208 may be disposed in an FFC or other beam coupler2216 to perform a variety of optical manipulations of an adjusted beam2214 (represented in FIG. 22A with different dashing than beam 2210).For example, free-space optics assembly 2208 may preserve the adjustedbeam characteristics of adjusted beam 2214. Process fiber 2204 may havethe same RIP as VBC delivery fiber 2240. Thus, the adjusted beamcharacteristics of adjusted beam 2214 may be preserved all the way toprocess head 2206. Process fiber 2204 may comprise a RIP similar to anyof the second lengths of fiber described above, including confinementregions.

Alternatively, as illustrated in FIG. 228, free-space optics assembly2208 may change the adjusted beam characteristics of adjusted beam 2214by, for example, increasing or decreasing the divergence, the beamdiameter, and/or the spot size of adjusted beam 2214 (e.g., bymagnifying or demagnifying adjusted beam 2214) and/or otherwise furthermodifying adjusted beam 2214. Furthermore, process fiber 2204 may have adifferent RIP than VBC delivery fiber 2240. Accordingly, the RIP ofprocess fiber 2204 may be selected to preserve additional adjustment ofadjusted beam 2214 made by the free-space optics of free-space opticsassembly 2208 to generate a twice adjusted beam 2224 (represented inFIG. 22B with different dashing than adjusted beam 2214).

FIG. 23 illustrates an example of a laser system 2300 including VBCfiber assembly 2302 disposed between feeding fiber 2312 and VBC deliveryfiber 2340. During operation, beam 2310 is coupled into VBC fiberassembly 2302 via feeding fiber 2312. VBC Fiber assembly 2302 includes afirst length of fiber 104, second length of fiber 108, and aperturbation device 110 and is configured to vary characteristics ofbeam 2310 in accordance with the various examples described above. VBCFiber assembly 2302 generates adjusted beam 2314 output by VBC deliveryfiber 2340. VBC delivery fiber 2340 comprises a second length of fiber108 of fiber for modifying, maintaining, and/or confining adjusted beamcharacteristics in a VBC fiber assembly 2302 in accordance with thevarious examples described above (see FIGS. 17-21, for example). VBCdelivery fiber 2340 couples adjusted beam 2314 into beam switch (“FFS”)2332, which then couples its various output beams to one or more ofmultiple process fibers 2304, 2320, and 2322. Process fibers 2304, 2320,and 2322 deliver adjusted beams 2314, 2328, and 2330 to respectiveprocess heads 2306, 2324, and 2326.

In an example, beam switch 2332 includes one or more sets of free-spaceoptics 2308, 2316, and 2318 configured to perform a variety of opticalmanipulations of adjusted beam 2314. Free-space optics 2308, 2316, and2318 may preserve or vary adjusted beam characteristics of adjusted beam2314. Thus, adjusted beam 2314 may be maintained by the free-spaceoptics or adjusted further. Process fibers 2304, 2320, and 2322 may havethe same or a different RIP as VBC delivery fiber 2340, depending onwhether it is desirable to preserve or further modify a beam passingfrom the free-space optics assemblies 2308, 2316, and 2318 to respectiveprocess fibers 2304, 2320, and 2322. In other examples, one or more beamportions of beam 2310 are coupled to a workpiece without adjustment, ordifferent beam portions are coupled to respective VBC fiber assembliesso that beam portions associated with a plurality of beamcharacteristics can be provided for simultaneous workpiece processing.Alternatively, beam 2310 can be switched to one or more of a set of VBCfiber assemblies.

Routing adjusted beam 2314 through any of free-space optics assemblies2308, 2316, and 2318 enables delivery of a variety of additionallyadjusted beams to process heads 2306, 2324, and 2326. Therefore, lasersystem 2300 provides additional degrees of freedom for varying thecharacteristics of a beam, as well as switching the beam between processheads (“time sharing”) and/or delivering the beam to multiple processheads simultaneously (“power sharing”).

For example, free-space optics in beam switch 2332 may direct adjustedbeam 2314 to free-space optics 2316 configured to preserve the adjustedcharacteristics of adjusted beam 2314. Process fiber 2304 may have thesame RIP as VBC delivery fiber 2340. Thus, the beam delivered to processhead 2306 will be a preserved adjusted beam 2314.

In another example, beam switch 2332 may direct adjusted beam 2314 tofree-space optics 2318 configured to preserve the adjustedcharacteristics of adjusted beam 2314. Process fiber 2320 may have adifferent RIP than VBC delivery fiber 2340 and may be configured withdivergence altering structures as described with respect to FIGS. 20 and21 to provide additional adjustments to the divergence distribution ofadjusted beam 2314. Thus, the beam delivered to process head 2324 willbe a twice adjusted beam 2328 having a different beam divergence profilethan adjusted beam 2314.

Process fibers 2304, 2320, and/or 2322 may comprise a RIP similar to anyof the second lengths of fiber described above, including confinementregions or a wide variety of other RIPs, and claimed subject matter isnot limited in this regard.

In yet another example, free-space optics beam switch 2332 may directadjusted beam 2314 to free-space optics 2308 configured to change thebeam characteristics of adjusted beam 2314. Process fiber 2322 may havea different RIP than VBC delivery fiber 2340 and may be configured topreserve (or alternatively further modify) the new further adjustedcharacteristics of adjusted beam 2314. Thus, the beam delivered toprocess head 2326 will be a twice adjusted beam 2330 having differentbeam characteristics (due to the adjusted divergence profile and/orintensity profile) than adjusted beam 2314.

In FIGS. 22A, 22B, and 23, the optics in the FFC or FFS may adjust thespatial profile and/or divergence profile by magnifying or demagnifyingthe adjusted beam 2214 before launching into the process fiber. They mayalso adjust the spatial profile and/or divergence profile via otheroptical transformations. They may also adjust the launch position intothe process fiber. These methods may be used alone or in combination.

FIGS. 22A, 22B, and 23 merely provide examples of combinations ofadjustments to beam characteristics using free-space optics and variouscombinations of fiber RIPs to preserve or modify adjusted beams 2214 and2314. The examples provided above are not exhaustive and are meant forillustrative purposes only. Thus, claimed subject matter is not limitedin this regard.

FIG. 24 illustrates various examples of perturbation devices,assemblies, or methods (for simplicity referred to collectively hereinas “perturbation device 110”) for perturbing a VBC fiber 200 and/or anoptical beam propagating in VBC fiber 200 according to various examplesprovided herein. Perturbation device 110 may be any of a variety ofdevices, methods, and/or assemblies configured to enable adjustment ofbeam characteristics of a beam propagating in VBC fiber 200. In anexample, perturbation device 110 may be a mandrel 2402, a micro-bend2404 in the VBC fiber 200, flexible tubing 2406, an acousto-optictransducer 2408, a thermal device 2410, a piezoelectric device 2412(e.g., transducer), a grating 2414, a clamp 2416 (or other fastener), amandrel-roller combination 2432, or the like, or any combinationthereof. These are merely examples of perturbation devices 110 and notan exhaustive listing of perturbation devices 110, and claimed subjectmatter is not limited in this regard.

Mandrel 2402 may be used to perturb VBC fiber 200 by providing a formabout which VBC fiber 200 may be bent. As discussed above, reducing thebend radius of VBC fiber 200 moves the intensity distribution of thebeam radially outward. In some examples, mandrel 2402 may be stepped orconically shaped to provide discrete bend radii levels. Alternatively,mandrel 2402 may comprise a cone shape without steps to providecontinuous bend radii for more granular control of the bend radius. Theradius of curvature of mandrel 2402 may be constant (e.g., a cylindricalform) or non-constant (e.g., an oval-shaped form). Similarly, flexibletubing 2406, clamps 2416 (or other varieties of fasteners), or rollers250 may be used to guide and control the bending of VBC fiber 200 aboutmandrel 2402. Furthermore, changing the length over which the fiber isbent at a particular bend radius also may modify the intensitydistribution of the beam. VBC fiber 200 and mandrel 2402 may beconfigured to change the intensity distribution within the first fiberpredictably (e.g., in proportion to the length over which the fiber isbent and/or the bend radius). Rollers 250 may move up and down along atrack 2442 on platform 2434 to change the bend radius of VBC fiber 200.

Clamps 2416 (or other fasteners) may be used to guide and control thebending of VBC fiber 200 with or without a mandrel 2402. Clamps 2416 maymove up and down along a track 2442 or platform 2446. Clamps 2416 mayalso swivel to change bend radius, tension, or direction of VBC fiber200. Controller 2448 may control the movement of clamps 2416.

In another example, perturbation device 110 may be flexible tubing 2406and may guide bending of VBC fiber 200 with or without a mandrel 2402.Flexible tubing 2406 may encase VBC fiber 200. Flexible tubing 2406 maybe made of a variety of materials and may be manipulated usingpiezoelectric transducers controlled by controller 2444. In anotherexample, clamps or other fasteners may be used to move flexible tubing2406.

Micro-bend 2404 in VBC fiber 200 is a local perturbation caused bylateral mechanical stress on the fiber. Micro-bending can cause modecoupling and/or transitions from one confinement region to anotherconfinement region within a fiber, resulting in varied beamcharacteristics of the beam propagating in a VBC fiber 200. Mechanicalstress may be applied by an actuator 2436 that is controlled bycontroller 2440. However, this is merely an example of a method forinducing mechanical stress in VBC fiber 200 and claimed subject matteris not limited in this regard.

Acousto-optic transducer (“AOT”) 2408 may be used to induce perturbationof a beam propagating in the VBC fiber 200 using an acoustic wave. Theperturbation is caused by the modification of the refractive index ofthe fiber by the oscillating mechanical pressure of an acoustic wave.The period and strength of the acoustic wave are related to the acousticwave frequency and amplitude, allowing dynamic control of the acousticperturbation. Thus, a perturbation device 110 including AOT 2408 may beconfigured to vary the beam characteristics of a beam propagating in thefiber. In an example, piezoelectric transducer 2418 may create theacoustic wave and may be controlled by controller or driver 2420. Theacoustic wave induced in AOT 2408 may be modulated to change and/orcontrol the beam characteristics of the optical beam in VBC fiber 200 inreal-time. However, this is merely an example of a method for creatingand controlling an AOT 2408 and claimed subject matter is not limited inthis regard.

Thermal device 2410 may be used to induce perturbation of a beampropagating in VBC fiber 200 using heat. The perturbation is caused bythe modification of the RIP of the fiber induced by heat. Perturbationmay be dynamically controlled by controlling an amount of heattransferred to the fiber and the length over which the heat is applied.Thus, a perturbation device 110 including thermal device 2410 may beconfigured to vary a range of beam characteristics. Thermal device 2410may be controlled by controller 2450.

Piezoelectric device 2412 may be used to induce perturbation of a beampropagating in a VBC fiber using piezoelectric action. The perturbationis caused by the modification of the RIP of the fiber induced by apiezoelectric material attached to the fiber. The piezoelectric materialin the form of a jacket around the bare fiber may apply tension orcompression to the fiber, modifying its refractive index via theresulting changes in density. Perturbation may be dynamically controlledby controlling a voltage to the piezoelectric device 2412. Thus, aperturbation device 110 including piezoelectric device 2412 may beconfigured to vary the beam characteristics over a particular range.

In an example, piezoelectric device 2412 may be configured to displaceVBC fiber 200 in a variety of directions (e.g., axially, radially,and/or laterally) depending on a variety of factors, including how thepiezoelectric device 2412 is attached to VBC fiber 200, the direction ofthe polarization of the piezoelectric materials, the applied voltage,etc. Additionally, bending of VBC fiber 200 is possible using thepiezoelectric device 2412. For example, driving a length ofpiezoelectric material having multiple segments comprising opposingelectrodes can cause a piezoelectric device 2412 to bend in a lateraldirection. Voltage applied to piezoelectric device 2412 by electrode2424 may be controlled by controller 2422 to control displacement of VBCfiber 200. Displacement may be modulated to change and/or control thebeam characteristics of the optical beam in VBC fiber 200 in real-time.However, this is merely an example of a method of controllingdisplacement of a VBC fiber 200 using a piezoelectric device 2412 andclaimed subject matter is not limited in this regard.

Gratings 2414 may be used to induce perturbation of a beam propagatingin a VBC fiber 200. A grating 2414 can be written into a fiber byinscribing a periodic variation of the refractive index into the core.Gratings 2414 such as fiber Bragg gratings can operate as opticalfilters or as reflectors. A long-period grating can induce transitionsamong co-propagating fiber modes. The radiance, intensity profile,and/or divergence profile of a beam comprised of one or more modes canthus be adjusted using a long-period grating to couple one or more ofthe original modes to one or more different modes having differentradiance and/or divergence profiles. Adjustment is achieved by varyingthe periodicity or amplitude of the refractive index grating. Methodssuch as varying the temperature, bend radius, and/or length (e.g.,stretching) of the fiber Bragg grating can be used for such adjustment.VBC fiber 200 having gratings 2414 may be coupled to stage 2426. Stage2426 may be configured to execute any of a variety of functions and maybe controlled by controller 2428. For example, stage 2426 may be coupledto VBC fiber 200 with fasteners 2430 and may be configured to stretchand/or bend VBC fiber 200 using fasteners 2430 for leverage. Stage 2426may have an embedded thermal device and may change the temperature ofVBC fiber 200.

FIG. 25 illustrates an example process 2500 for adjusting and/ormaintaining beam characteristics within a fiber without the use offree-space optics to adjust the beam characteristics. In block 2502, afirst length of fiber and/or an optical beam are perturbed to adjust oneor more optical beam characteristics. Process 2500 moves to block 2504,where the optical beam is launched into a second length of fiber.Process 2500 moves to block 2506, where the optical beam having theadjusted beam characteristics is propagated in the second length offiber. Process 2500 moves to block 2508, where at least a portion of theone or more beam characteristics of the optical beam are maintainedwithin one or more confinement regions of the second length of fiber.The first and second lengths of fiber may be comprised of the samefiber, or they may be different fibers.

Systems for Processing Using Adjustable Beam Characteristics

A system for processing can comprise, for example, VBC fiber 100,including first length of fiber 104 and second length of fiber 108, andperturbation device 110 in order to control one or more beamcharacteristics of optical beam 102, per FIG. 1. Such a system forprocessing can comprise, for example, VBC fiber 200, including firstlength of fiber 204 and second length of fiber 208, and perturbationdevice 210 in order to control one or more beam characteristics ofoptical beam 202, per FIG. 2.

Such a system for processing can comprise, for example, first length offiber 1100, per FIG. 11; first length of fiber 2100, per FIG. 12; firstlength of fiber 1300, per FIG. 13; first length of fiber 1400, per FIG.14A; first length of fiber 1406, per FIG. 14B; first length of fiber1500, per FIG. 15; or first length of fiber 1600, per FIG. 16.

Such a system for processing can comprise, for example, second length offiber 1700, per FIG. 17; second length of fiber 1800, per FIG. 18;second length of fiber 1900, per FIG. 19; second length of fiber 2000,per FIG. 20; or second length of fiber 2100, per FIG. 21.

In some examples, a first length of fiber, a second length of fiber, anda perturbation device can be combined in a fiber assembly, such as VBCfiber assembly 2202, per FIG. 22A or FIG. 22B; or VBC fiber assembly2302, per FIG. 23.

A perturbation device (e.g., perturbation device 110) can be configuredto modify one or more beam characteristics of optical beam (e.g.,optical beam 102), during processing, in the first length of fiber(e.g., first length of fiber 104), in the second length of fiber (e.g.,second length of fiber 108), or in the first and second lengths offiber.

In some examples, the perturbation device (e.g., perturbation device110) can modify one or more beam characteristics of an optical beam(e.g., optical beam 102). The modified one or more beam characteristicscan include, for example, one or more of angular distribution, azimuthalintensity distribution, beam diameter, beam profile (e.g., Gaussian,flat-top), beam shape, divergence, divergence profile, divergencedistribution, BPP, intensity distribution, luminance, M² factor, NA,optical intensity, optical mode (e.g., filtering), power density, radialbeam position, radiance, spatial profile distribution, spot shape, orspot size, or any combination thereof.

In some examples, the perturbing effectuated by the perturbation device(e.g., perturbation device 110) can include one or more of bending,bending over a particular length, micro-bending, applying acousto-opticexcitation, thermal perturbation, stretching, applying piezoelectricperturbation, applying clamps (or other fasteners), using a grating, orany combination thereof. FIG. 24 illustrates various examples of suchperturbation devices.

Such a system for processing can further comprise, for example, one ormore optical beam sources configured to generate optical beams, such aslaser beams associated with fiber-coupled lasers (e.g., disk lasers,diode lasers, fiber lasers, YAG lasers), per FIGS. 22A, 22B, and/or 23.

Such a system for processing can further comprise, for example, one ormore beam couplers, beam switches, free-space optics assemblies, processheads, or any combination thereof. In some examples, characteristics ofan adjusted beam (e.g., adjusted beam 2214) from a VBC fiber assembly(e.g., VBC fiber assembly 2202) can be preserved in a delivery fiber(e.g., VBC delivery fiber 2240), free-space optics assembly (e.g.,free-space optics assembly 2208), process fiber (e.g., process fiber2204), and/or process head (process head 2206), per FIG. 22A. In someexamples, characteristics of an adjusted beam (e.g., adjusted beam 2214)from a VBC fiber assembly (e.g., VBC fiber assembly 2202) can bepreserved in a delivery fiber (e.g., VBC delivery fiber 2240), but thenfurther modified in a free-space optics assembly (e.g., free-spaceoptics assembly 2208), and then the twice-adjusted beam can be preservedin a process fiber (e.g., process fiber 2204) and/or process head(process head 2206), per FIG. 228. In some examples, characteristics ofan adjusted beam (e.g., adjusted beam 2314) from a VBC fiber assembly(e.g., VBC fiber assembly 2302) can be preserved in a delivery fiber(e.g., VBC delivery fiber 2340), but then switched using a beam switch(e.g., beam switch 2332) and preserved or further modified in one ormore free-space optics assemblies (e.g., free-space optics assemblies2308, 2316, 2318), and then the once-or-twice-adjusted beams can bepreserved in one or more process fibers (e.g., process fiber 2304, 2320,2322) and/or one or more process heads (e.g., process head 2306, 2324,2326), per FIG. 23. Such a system provides for options such as powersharing and time sharing as discussed.

Methods of Processing Using Adjustable Beam Characteristics

FIG. 29 depicts a first example method of processing by controlling oneor more beam characteristics of an optical beam. In some examples, theprocessing can include additive processing and/or manufacture of aproduct. In some examples, the processing can include one or more ofablating, cladding, cutting, drilling, engraving, glazing,heat-treating, marking, patterning, roughening, smoothing, surfacetexturing, trepanning, and/or welding, or any combination thereof.

In block 2902, the optical beam is launched into a first length of fiberhaving a first RIP. In block 2904, one or more beam characteristics ofthe optical beam can be modified in the first length of fiber. Suchmodified beam characteristics can include, for example, angulardistribution, azimuthal intensity distribution, beam diameter, beamdivergence distribution, BPP, beam profile (e.g., Gaussian, flat-top),beam shape, divergence, divergence profile, intensity distribution,luminance, M² factor, NA, optical intensity profile, optical mode (e.g.,filtering), power density profile, radial beam position, radiance,spatial profile distribution, spot shape, spot size, or the like, or anycombination thereof. In some examples, the one or more beamcharacteristics of the optical beam can be modified in the first lengthof fiber (block 2904), in the second length of fiber (block 2908), or inthe first and second lengths of fiber (blocks 2904 and 2908).

In block 2906, the optical beam is coupled from the first length offiber into a second length of fiber having a second RIP and one or moreconfinement regions. In some examples, when the second length of fiberhas one confinement region, the first RIP can differ from the secondRIP; but when the second length of fiber has two or more confinementregions, the first RIP can be the same as or differ from the second RIP.

In block 2908, the one or more beam characteristics of the optical beamcan be modified in the second length of fiber. Such modified beamcharacteristics can include, for example, azimuthal intensitydistribution. In some examples, the one or more beam characteristics ofthe optical beam can be modified in the first length of fiber (block2904), in the second length of fiber (block 2908), or in the first andsecond lengths of fiber (blocks 2904 and 2908).

In block 2910, the modified one or more beam characteristics of theoptical beam are confined within the one or more confinement regions ofthe second length of fiber. In block 2912, an output beam, having themodified one or more beam characteristics of the optical beam, isgenerated from the second length of fiber.

Similarly, FIG. 30 depicts a second example method of processing bycontrolling one or more beam characteristics of an optical beam. In someexamples, the processing can include additive processing and/ormanufacture of a product. In some examples, the process can include oneor more of ablating, cladding, cutting, drilling, engraving, glazing,heat-treating, marking, patterning, roughening, smoothing, surfacetexturing, trepanning, and/or welding, or any combination thereof.

In block 3002, the optical beam is launched into a first length of fiberhaving a first RIP. In block 3004, one or more beam characteristics ofthe optical beam can be modified in the first length of fiber. Suchmodified beam characteristics can include, for example, angulardistribution, azimuthal intensity distribution, beam diameter, beamdivergence distribution, BPP, beam profile (e.g., Gaussian, flat-top),beam shape, divergence, divergence profile, intensity distribution,luminance, M² factor, NA, optical intensity profile, optical mode (e.g.,filtering), power density profile, radial beam position, radiance,spatial profile distribution, spot shape, spot size, or the like, or anycombination thereof. In some examples, the one or more beamcharacteristics of the optical beam can be modified in the first lengthof fiber (block 3004), in the second length of fiber (block 3008), or inthe first and second lengths of fiber (blocks 3004 and 3008).

In block 3006, the optical beam is coupled from the first length offiber into a second length of fiber having a second RIP and two or moreconfinement regions. In some examples, the first RIP can be the same asor differ from the second RIP.

In block 3008, the one or more beam characteristics of the optical beamcan be modified in the second length of fiber. Such modified beamcharacteristics can include, for example, azimuthal intensitydistribution. In some examples, the one or more beam characteristics ofthe optical beam can be modified in the first length of fiber (block3004), in the second length of fiber (block 3008), or in the first andsecond lengths of fiber (blocks 3004 and 3008).

In block 3010, the modified one or more beam characteristics of theoptical beam are confined within the two or more confinement regions ofthe second length of fiber. In block 3012, an output beam, having themodified one or more beam characteristics of the optical beam, isgenerated from the second length of fiber.

In some examples, the method can further comprise: adjusting an angulardistribution of the output beam for ablating, cladding, cutting,drilling, engraving, glazing, heat-treating, marking, patterning,roughening, smoothing, surface texturing, trepanning, and/or welding oneor more parts of a product. For example, the angular distribution can beadjusted to increase or decrease the divergence, to change the axis ofsymmetry, to make it symmetrical or asymmetrical, or to change the ratioof asymmetry.

In some examples, the method can further comprise: adjusting anazimuthal intensity distribution of the output beam for ablating,cladding, cutting, drilling, engraving, glazing, heat-treating, marking,patterning, roughening, smoothing, surface texturing, trepanning, and/orwelding one or more parts of a product. For example, the azimuthalintensity distribution can be adjusted to make it symmetrical orasymmetrical, or to change the ratio of asymmetry.

In some examples, the method can further comprise: adjusting a beamdiameter of the output beam for ablating, cladding, cutting, drilling,engraving, glazing, heat-treating, marking, patterning, roughening,smoothing, surface texturing, trepanning, and/or welding one or moreparts of a product. For example, the beam diameter can be greater thanor equal to 1 μm and less than or equal to 1,000 μm; greater than orequal to 1 μm and less than or equal to 100 μm (e.g., for additivemanufacturing); greater than or equal to 100 μm and less than or equalto 500 μm (e.g., for welding); or greater than or equal to 500 μm andless than or equal to 1,000 μm (e.g., for cladding).

In some examples, the method can further comprise: adjusting a beamdivergence distribution of the output beam for ablating, cladding,cutting, drilling, engraving, glazing, heat-treating, marking,patterning, roughening, smoothing, surface texturing, trepanning, and/orwelding one or more parts of a product. For example, the beam divergencedistribution can be adjusted to make it symmetrical or asymmetrical.

In some examples, the method can further comprise: adjusting a BPP ofthe output beam for ablating, cladding, cutting, drilling, engraving,glazing, heat-treating, marking, patterning, roughening, smoothing,surface texturing, trepanning, and/or welding one or more parts of aproduct. For example, the BPP can be greater than or equal to 1 mm-mradand less than or equal to 50 mm-mrad; greater than or equal to 1 mm-mradand less than or equal to 10 mm-mrad; or greater than or equal to 10mm-mrad and less than or equal to 50 mm-mrad.

In some examples, the method can further comprise: adjusting a beamprofile (e.g., Gaussian, flat-top) of the output beam for ablating,cladding, cutting, drilling, engraving, glazing, heat-treating, marking,patterning, roughening, smoothing, surface texturing, trepanning, and/orwelding one or more parts of a product. For example, the beam profilecan be adjusted to make it Gaussian or more Gaussian, flat-topped ormore flat-topped, ring/donut shaped, or an azimuthally non-symmetricpower distribution profile.

In some examples, the method can further comprise: adjusting a beamshape of the output beam for ablating, cladding, cutting, drilling,engraving, glazing, heat-treating, marking, patterning, roughening,smoothing, surface texturing, trepanning, and/or welding one or moreparts of a product. For example, the beam shape can be adjusted to makeit symmetrical or asymmetrical.

In some examples, the method can further comprise: adjusting adivergence of the output beam for ablating, cladding, cutting, drilling,engraving, glazing, heat-treating, marking, patterning, roughening,smoothing, surface texturing, trepanning, and/or welding one or moreparts of a product. For example, the divergence can be greater than orequal to 10 mrad and less than or equal to 500 mrad; greater than orequal to 10 mrad and less than or equal to 200 mrad (e.g., glass-guidedoptical beam); greater than or equal to 50 mrad and less than or equalto 200 mrad (e.g., glass-guided optical beam); or greater than or equalto 50 mrad and less than or equal to 500 mrad (e.g., glass- orpolymer-guided optical beam).

In some examples, the method can further comprise: adjusting adivergence profile of the output beam for ablating, cladding, cutting,drilling, engraving, glazing, heat-treating, marking, patterning,roughening, smoothing, surface texturing, trepanning, and/or welding oneor more parts of a product. For example, the divergence profile can beadjusted to make it symmetrical or asymmetrical.

In some examples, the method can further comprise: adjusting anintensity distribution of the output beam for ablating, cladding,cutting, drilling, engraving, glazing, heat-treating, marking,patterning, roughening, smoothing, surface texturing, trepanning, and/orwelding one or more parts of a product. For example, the intensitydistribution can be adjusted to make it symmetrical or asymmetrical.

In some examples, the method can further comprise: adjusting a luminanceof the output beam for ablating, cladding, cutting, drilling, engraving,glazing, heat-treating, marking, patterning, roughening, smoothing,surface texturing, trepanning, and/or welding one or more parts of aproduct.

In some examples, the method can further comprise: adjusting an M²factor of the output beam for ablating, cladding, cutting, drilling,engraving, glazing, heat-treating, marking, patterning, roughening,smoothing, surface texturing, trepanning, and/or welding one or moreparts of a product. For example, the M² factor can be greater than orequal to 1 and less than or equal to 100; greater than or equal to 1 andless than or equal to 10; greater than or equal to 3 and less than orequal to 30; greater than or equal to 4 and less than or equal to 20; orgreater than or equal to 5 and less than or equal to 100.

In some examples, the method can further comprise: adjusting an NA ofthe output beam for ablating, cladding, cutting, drilling, engraving,glazing, heat-treating, marking, patterning, roughening, smoothing,surface texturing, trepanning, and/or welding one or more parts of aproduct. For example, the NA can be greater than or equal to 0.01 andless than or equal to 0.50; greater than or equal to 0.05 and less thanor equal to 0.25; greater than or equal to 0.01 and less than or equalto 0.20 (e.g., glass-guided optical beam); greater than or equal to 0.05and less than or equal to 0.20 (e.g., glass-guided optical beam); orgreater than or equal to 0.05 and less than or equal to 0.50 (e.g.,glass- or polymer-guided optical beam).

In some examples, the method can further comprise: adjusting an opticalintensity profile of the output beam for ablating, cladding, cutting,drilling, engraving. glazing, heat-treating, marking, patterning,roughening, smoothing, surface texturing, trepanning, and/or welding oneor more parts of a product. For example, the optical intensity profilecan be adjusted to make to shift intensity toward or away from a centerof the output beam.

In some examples, the method can further comprise: adjusting an opticalmode (e.g., filtering) of the output beam for ablating, cladding,cutting, drilling, engraving, glazing, heat-treating, marking,patterning, roughening, smoothing, surface texturing, trepanning, and/orwelding one or more parts of a product. For example, the optical modecan be adjusted to filter out higher order modes from the output beam,or to intentionally add higher order mode shapes.

In some examples, the method can further comprise: increasing powerdensity of the output beam for ablating, cladding, cutting, drilling,engraving, glazing, marking, patterning, roughening, surface texturing,trepanning, and/or welding one or more parts of a product. In someexamples, the method can further comprise: decreasing power density ofthe output beam for cutting, engraving, glazing, heat-treating, marking,patterning, smoothing, surface texturing, and/or trepanning one or moreparts of the product.

In some examples, the method can further comprise: adjusting a radialbeam position of the output beam for ablating, cladding, cutting,drilling, engraving, glazing, heat-treating, marking, patterning,roughening, smoothing, surface texturing, trepanning, and/or welding oneor more parts of a product. For example, the radial beam position can becloser to a center of a process fiber or farther from the center of theprocess fiber.

In some examples, the method can further comprise: adjusting a radianceof the output beam for ablating, cladding, cutting, drilling, engraving,glazing, heat-treating, marking, patterning, roughening, smoothing,surface texturing, trepanning, and/or welding one or more parts of aproduct.

In some examples, the method can further comprise: adjusting a spatialprofile distribution of the output beam for ablating, cladding, cutting,drilling, engraving, glazing, heat-treating, marking, patterning,roughening, smoothing, surface texturing, trepanning, and/or welding oneor more parts of a product. For example, the spatial profiledistribution can be adjusted to make it symmetrical or asymmetrical.

In some examples, the method can further comprise: increasing beamdiameter and/or spot size of the output beam for heat-treating and/orsmoothing one or more parts of a product. A larger beam diameter and/orspot size can optimize build rate by covering more area during a givenperiod of time, while a smaller beam diameter and/or spot size canimprove the quality of an edge or surface qualities of a product beingmanufactured. Such improvements can drastically enhance build rateand/or feature resolution of the product.

The spot shape can vary, depending on intended use. For example, thespot shape can be round, elliptical, donut shaped, or any combinationthereof (e.g., a round portion in the center surrounded by a donutshape). For example, the spot shape can be azimuthally symmetric orazimuthally asymmetric.

FIG. 31 depicts a plan view of a build layer 3100 having a first region3102 and a second region 3104. A scan direction 3106 provides an examplepath of an optical beam as it travels across the build layer 3100. Whileonly a single pass of the optical beam is illustrated, multiple passescan be made across all or a portion of the build layer 3100, as desired,using almost any combination of scan directions to yield virtually anydesired scan pattern. In addition, passes can be linear or non-linear,as desired. For optimum flexibility, one or more beam characteristics ofthe optical beam can be modified prior to and/or during any given pass.

As the optical beam travels across the build layer 3100, it initiallyencounters first region 3102, in which it can be desired to optimizesurface roughness. A smaller beam diameter and/or spot size can beselected, for example, automatically or by an operator, to improve thequality of the surface finish in order to optimize surface roughness infirst region 3102. As the optical beam continues across the build layer3100, it encounters second region 3104, in which it can be desired tooptimize build rate. A larger beam diameter and/or spot size can beselected, for example, automatically or by an operator, to optimizebuild rate by covering more area during a given period of time in secondregion 3104. As the optical beam continues across the build layer 3100,it again encounters first region 3102, in which it can be desired tooptimize surface roughness. Once again, a smaller beam diameter and/orspot size can be selected, for example, automatically or by an operator,to improve the quality of the surface finish in order to optimizesurface roughness in first region 3102.

At some point during the creation of a layer-based 3D object, everyportion of the material for the 3D object is either exposed or liesimmediately under the surface of a thinly deposited or processed layer,which is often referred to as a “build layer” in the additivemanufacturing art. This level of access to the material for the 3Dobject of the build layer allows for additional processing by an optical(e.g., laser) beam.

Initially, a first layer of particles is positioned on a build plate.The particles can be free-flowing (e.g., a dry powder), in the form of apaste or wire (e.g., solid particles), or in any other form suitable foradditive manufacturing. The particles can comprise metal materials,non-metal materials, or mixtures of both. Particles comprising metalmaterials can include any metals or metal-containing compounds,including alloys and mixtures of various metallic compounds (e.g., metaloxides, metal carbides, metal nitrides, etc.) that are suitable foradditive manufacturing. Non-metals can include any non-metal materialssuitable for additive manufacturing, such as, for example, ceramics,polymers, or waxes.

The first layer of particles is heated by an optical beam sufficientlyto fuse the particles together to form a first build layer. The opticalbeam employed for exposing the first build layer is emitted from anoptical fiber, such as from any of the lasers disclosed in thisapplication. One or more beam characteristics of the optical beam can bemodified prior to and/or during the exposing of the first build layer.As disclosed in this application, the modifying of the optical beamoccurs prior to the optical beam being outputted from the optical fiber.

After forming the first build layer, a second layer of particles ispositioned on the exposed first build layer. The second layer ofparticles is heated by the optical beam sufficiently to fuse theparticles together to form a second build layer. The optical beamemployed for exposing the second build layer is emitted from the opticalfiber, such as from any of the lasers disclosed in this application. Oneor more beam characteristics of the optical beam can be modified priorto and/or during the exposing of the second build layer. As disclosed inthis application, the modifying of the optical beam occurs prior to theoptical beam being outputted from the optical fiber.

The positioning of another layer of particles and subsequent heating ofthe another layer of particles can be repeated as necessary to form the3D object.

The modifying of the one or more beam characteristics of the opticalbeam in the first length of fiber, in the second length of fiber, or inthe first and second lengths of fiber can be performed by any of thetechniques disclosed in this application. For example, the modifying ofthe one or more beam characteristics can comprise modifying one or moreof angular distribution, azimuthal intensity distribution, beamdiameter, beam divergence distribution, BPP, beam profile (e.g.,Gaussian, flat-top), beam shape, divergence, divergence profile,intensity distribution, luminance, M² factor, NA, optical intensityprofile, optical mode (e.g., filtering), power density profile, radialbeam position, radiance, spatial profile distribution, spot shape, spotsize, or the like, or any combination thereof.

In some examples, the modifying of the one or more beam characteristicsis carried out without the use of free-space optics, as disclosed inthis application. Without such free-space optics, the resulting abilityto quickly modify the one or more beam characteristics of the opticalbeam can allow, for example, switching among beam shapes on the fly(e.g., without slowing or stopping a pass of the optical beam), therebyproviding corresponding manufacturing efficiencies, and allowingefficient tailoring of temperature profiles and the resulting stressstates in a 3D object being manufactured. For example, free-space opticscan allow such modifications over times on the order of hundreds ofmilliseconds, whereas in-fiber solutions could allow such modificationsover times on the order of hundreds of microseconds or single-digitmilliseconds.

In some examples, more than one laser can be used for the method ofprocessing (e.g., a first laser for pre-heating powder, a second laserfor fusing powder, and/or a third laser for post-heating powder). Inparticular, more than one laser with a variable BPP system as disclosedin this application could provide enhanced performance (e.g., improvedpart quality, part utility, and/or production speed) and/or increasedflexibility (e.g., in process, machine, or plant design and/oroperation).

In some examples, more than one laser can be used for the method ofprocessing (e.g., stopping at points while a 3D object is being builtusing a first laser, and using a second laser to anneal, normalize,solutionize, stress relieve, temper, etc. the 3D object). In thisexample, the second laser could emit a larger, uniform beam and, thus,would not require the variable BPP system as disclosed in thisapplication.

In some examples, the ability to quickly modify the one or more beamcharacteristics of the optical beam, using a laser with a variable BPPsystem as disclosed in this application, would allow the same laser tobe used for the entire method of processing, thereby providingcorresponding manufacturing efficiencies.

FIG. 32 depicts an elevation view of a 3D object 3200 manufactured usinga powder bed process.

In some examples, the powder bed process can use one or more layers,such as first layer 3202 a, second layer 3202 b, third layer 3202 c,fourth layer 3202 d, fifth layer 3202 e, sixth layer 3202 f, seventhlayer 3202 g, eighth layer 3202 h, ninth layer 3202 i, tenth layer 3202j, and eleventh layer 3202 k. However, any number of layers can be used.For example, the number of layers can be greater than or equal to 1 andless than or equal to 100,000; greater than or equal to 10 and less thanor equal to 10,000; or be greater than or equal to 100 and less than orequal to 1,000.

Depending on the processing, the one or more layers (e.g., first layer3202 a, second layer 3202 b, third layer 3202 c, fourth layer 3202 d,fifth layer 3202 e, sixth layer 3202 f, seventh layer 3202 g, eighthlayer 3202 h, ninth layer 3202 i, tenth layer 3202 j, or eleventh layer3202 k, or any combination thereof) can comprise powder that is the samein each layer, different in each layer, the same in two or more layers,different in two or more layers, the same in alternating layers,different in alternating layers, the same in bottom and top layers, etc.

When building a complex 3D object, such as 3D object 3200, supportingstructures can be incorporated that stay in place until 3D object 3200is completed (after which the supporting structures are removed). Insome examples, the powder bed process can use one or more supportingstructures, such as first supporting structures 3204 a, secondsupporting structures 3204 b, and third supporting structures 3204 c.However, any number of supporting structures can be used. For example,the number of supporting structures can be greater than or equal to 1and less than or equal to 1,000,000, but the number of supportingstructures could exceed 1,000,000.

As shown in FIG. 32, optical beam source 3206 can generate optical beam3208 to selectively heat the one or more layers (e.g., first layer 3202a, second layer 3202 b, third layer 3202 c, fourth layer 3202 d, fifthlayer 3202 e, sixth layer 3202 f, seventh layer 3202 g, eighth layer3202 h, ninth layer 3202 i, tenth layer 3202 j, or eleventh layer 3202k, or any combination thereof) of powder sufficiently to fuse some ofthe particles together to form 3D object 3200, first supportingstructures 3304 a, second supporting structures 3204 b, and/or thirdsupporting structures 3204 c.

FIG. 33 depicts a plan view of the 3D object 3200 at a first pointduring the powder bed process. The 3D object 3200 starts with a layer ofparticles 3300 forming a powder bed positioned on a build plate (notshown) so as to be exposed. The layer of particles 3300 is selectivelyheated by an optical beam sufficiently to fuse some of the particlestogether to form a first portion 3302 of 3D object 3200 and four firstsupporting structures 3304 a. One or more beam characteristics of theoptical beam can be modified prior to and/or during the selectiveheating of the layer of particles 3300 (different beam characteristicscan be desired, for example, when forming a relatively permanent 3Dobject as opposed to a relatively temporary supporting structure).

The remaining particles in the layer of particles 3300 of the powder bedremain unfused. The positioning of another layer of particles andsubsequent heating of the another layer of particles is repeated,continuing to build the first portion 3302 of 3D object 3200 and thefour first supporting structures 3304 a.

FIG. 34 depicts a plan view of a 3D object at a second point during thepowder bed process. A layer of particles 3400 is positioned on theprevious layer so as to be exposed. The layer of particles 3400 isselectively heated by an optical beam sufficiently to fuse some of theparticles together to form a first portion 3402 of 3D object 3200, asecond portion 3406 of 3D object 3200, four first supporting structures3404 a, and four second supporting structures 3404 b. One or more beamcharacteristics of the optical beam can be modified prior to and/orduring the selective heating of the layer of particles 3400 (differentbeam characteristics can be desired, for example, when the materialunderlying a layer of particles is unfused powder as opposed to when thematerial underlying the layer of particles is a solid of fused material;different beam characteristics can be desired, for example, when forminga relatively permanent 3D object as opposed to a relatively temporarysupporting structure).

The remaining particles in the layer of particles 3400 of the powder bedremain unfused. The positioning of another layer of particles andsubsequent heating of the another layer of particles is repeated,continuing to build the first portion 3402 of 3D object 3200, the secondportion 3406 of 3D object 3200, and the four second supportingstructures 3404 b (the four first supporting structures 3404 a do notextend upward beyond the layer of particles 3400).

FIG. 35 depicts a plan view of a 3D object at a third point during thepowder bed process. A layer of particles 3500 is positioned on theprevious layer so as to be exposed. The layer of particles 3500 isselectively heated by an optical beam sufficiently to fuse some of theparticles together to form a first portion 3502 of 3D object 3200, asecond portion 3506 of 3D object 3200, a third portion 3508 of 3D object3200, four second supporting structures 3504 b, and four thirdsupporting structures 3504 c (the four first supporting structures 3404a did not extend upward beyond the layer of particles 3400, but areshown for clarity). One or more beam characteristics of the optical beamcan be modified prior to and/or during the selective heating of thelayer of particles 3500 (different beam characteristics can be desired,for example, when the material underlying a layer of particles isunfused powder as opposed to when the material underlying the layer ofparticles is a solid of fused material; different beam characteristicscan be desired, for example, when forming a relatively permanent 3Dobject as opposed to a relatively temporary supporting structure).

The remaining particles in the layer of particles 3500 of the powder bedremain unfused. The positioning of another layer of particles andsubsequent heating of the another layer of particles is repeated,continuing to build the first portion 3502 of 3D object 3200, the secondportion 3506 of 3D object 3200, the third portion 3508 of 3D object3200, and the four third supporting structures 3504 c (the four secondsupporting structures 3504 b do not extend upward beyond the layer ofparticles 3500).

FIG. 36 depicts a plan view of a 3D object at a fourth point during thepowder bed process. A layer of particles 3600 is positioned on theprevious layer so as to be exposed. The layer of particles 3600 isselectively heated by an optical beam sufficiently to fuse some of theparticles together to form a first portion 3602 of 3D object 3200, asecond portion 3606 of 3D object 3200, a third portion 3608 of 3D object3200, a fourth portion 3610 of 3D object 3200, and four third supportingstructures 3604 c (the four first supporting structures 3404 a did notextend upward beyond the layer of particles 3400 and the four secondsupporting structures 3504 b did not extend upward beyond the layer ofparticles 3500, but are shown for clarity). One or more beamcharacteristics of the optical beam can be modified prior to and/orduring the selective heating of the layer of particles 3600 (differentbeam characteristics can be desired, for example, when the materialunderlying a layer of particles is unfused powder as opposed to when thematerial underlying the layer of particles is a solid of fused material;different beam characteristics can be desired, for example, when forminga relatively permanent 3D object as opposed to a relatively temporarysupporting structure).

The remaining particles in the layer of particles 3600 of the powder bedremain unfused. The positioning of another layer of particles andsubsequent heating of the another layer of particles are not repeated,because 3D object 3200 is now complete.

In some examples, the method can further comprise: using the output beamfor ablating, cladding, cutting, drilling, engraving, glazing,heat-treating, marking, patterning, roughening, smoothing, surfacetexturing, trepanning, and/or welding one or more parts of a product.The using of the output beam can occur, for example, during and/or aftermanufacture of the product.

FIG. 37 depicts a plan view of a portion of a 3D object after fusing.Portion 3710 of 3D object 3200 can be a product for which furtherprocessing is desired or required. Such further processing can include,for example, one or more of ablating and/or engraving 3712; cutting3714; drilling and/or trepanning 3716; heat-treating 3718; marking 3720;or engraving, patterning, roughening, and/or surface texturing 3722, orany combination thereof.

FIG. 38A depicts an elevation view of a 3D object after fusing. 3Dobject 3200 can be a product for which further processing is desired orrequired. FIG. 38B depicts an elevation view of a 3D object after fusingand such further processing. The further processing can include, forexample, one or more of glazing, smoothing, or a combination thereof. Asdeposited or as deposited and fused, 3D object 3200 can have portions3824 a, 3824 b that include significant irregularities. As understood bya PHOSITA, one or more of glazing, smoothing, or a combination thereofcan reduce the irregularities, for example, of portion 3824 b to that ofportion 3824 c or similar.

During operations that remove material (e.g., ablating, cutting,drilling, engraving, trepanning), laser cutting speed (e.g., materialfeed rate) and/or laser output power can affect kerf width. Generally,kerf width increases for lower cutting speeds and higher laser powers.

Also, during operations that remove material (e.g., ablating, cutting,drilling, engraving, trepanning), high pressure assist gas can be usedto prevent or limit oxidation reactions in the removal area, to evacuatemelted material from the kerf, to add heat input to the process, or toremove heat from the process. The assist gas and/or the pressure of theassist gas can be selected, for example, automatically or by an operatorfrom one or more sources. The assist gas itself can include one or moreof air, argon, helium, nitrogen, oxygen, other gases known to a personhaving ordinary skill in the art, or any combination thereof.

Depending on the processing, values of the assist gas pressure canrange, for example, from less than 1 pound per square inch gage (“psig”)to more than 500 psig; greater than or equal to 1 psig and less than orequal to 10 psig; greater than or equal to 1 psig and less than or equalto 50 psig; or greater than or equal to 50 psig and less than or equalto 500 psig. The pressure can be constant during a given processing orcan be changed at least once during the processing, such as whenchanging the assist gas, when modifying the one or more beamcharacteristics, and/or when starting or finishing any individual passof a scan pattern.

In some examples, the method can further comprise: modulating the outputbeam while ablating, cladding, cutting, drilling, engraving, glazing,heat-treating, marking, patterning, roughening, smoothing, surfacetexturing, trepanning, and/or welding one or more parts of a product.The modulating of the output beam can occur, for example, during and/orafter manufacture of the product.

Modulating of the output beam can involve starting and stopping ofgeneration of the output beam (e.g., effectively turning the output beamon and off). In some examples, the output beam can be generated as aseries of pulses. A pulse indicates that the output beam is beinggenerated (e.g., is on), and the absence of a pulse indicates that theoutput beam is not being generated (e.g., is off).

In some examples, the output beam can be modulated at a selectedfrequency (typically expressed in cycles/second or Hertz (“Hz”). Themodulation frequency can be selected, for example, automatically or byan operator from one or more discrete values or from a continuous rangeof values.

Depending on the processing, values of the modulation frequency can be,for example, greater than or equal to 1 Hz and less than or equal to100,000 Hz (100 kHz); greater than or equal to 1 Hz and less than orequal to 500 Hz; greater than or equal to 500 Hz and less than or equalto 5,000 Hz (5 kHz); or greater than or equal to 5,000 Hz (5 kHz) andless than or equal to 100,000 Hz (100 kHz). The modulation frequency canbe constant during a given processing or can be changed at least onceduring the processing, such as when modifying the one or more beamcharacteristics and/or when starting or finishing any individual pass ofa scan pattern.

In some examples, the output beam can be modulated at a selected dutycycle, where the duty cycle is the fraction of a period during which theoutput beam is on (typically expressed in percent). The duty cycle caninfluence heat input and/or the heating rate. The duty cycle can beselected, for example, automatically or by an operator from one or morediscrete values or from a continuous range of values from 0% to 100%.Depending on the processing, values of the duty cycle can include, forexample, 0% (always off); 10%; 20%; 25%; 30%; 40%; 50% (half on, halfoff); 60%; 70%; 75%; 80%; 90%; or 100% (always on). Values of the dutycycle also can include, for example, about 10%; about 20%; about 30%;about 40%; about 50%; about 60%; about 70%; about 80%; or about 90%. Theduty cycle can be constant during a given processing or can be changedat least once during the processing.

In some examples, the method can further comprise: in additiveprocessing, alternately using the output beam to pre-heat powder priorto fusing the powder and using the output beam to fuse the powder.

In additive processing, it can be desirable to pre-heat and/or post-heatthe associated powder, as well as to fuse the powder. In contrast tostandard commercial AM systems the pre-heating can raise the temperatureof the associated powder in a powder bed and/or an associated substrateabove 200° C. (e.g., for control of moisture), above 500° C. (e.g., forcontrol of residual stresses), or above 1,000° C. (e.g., for control ofmicrostructure evolution). Such pre-heating can improve, for example,crack mitigation, distortion control, and/or microstructure control. Thehigher temperatures generally correlate with the processing of metals,while the lower temperatures generally correlate with the processing ofpolymers.

In such processing, the output beam can be used to pre-heat powder priorto fusing the powder, and also used to fuse the powder. The output beamcan be alternated back and forth between pre-heating the powder andfusing the powder, being changed, for example, when modifying the one ormore beam characteristics, during any individual pass of a scan pattern,and/or when starting or finishing any individual pass of the scanpattern.

In some examples, the method can further comprise: in additiveprocessing, alternately using the output beam to pre-heat powder priorto fusing the powder and using the output beam to post-heat the fusedpowder.

As discussed above, in additive processing, it can be desirable topre-heat and/or post-heat the associated powder, as well as to fuse thepowder. The pre-heating can raise the temperature of the associatedpowder in a powder bed and/or an associated substrate above 100° C.,above 300° C. (e.g., lower temperature melt alloys), or above 600° C.(higher temperature melt alloys). As before, the higher temperaturesgenerally correlate with the processing of metals, while the lowertemperatures generally correlate with the processing of polymers.

In such processing, the output beam can be used to pre-heat powder priorto fusing the powder, and also used to post-heat the fused powder. Theoutput beam can be alternated back and forth between pre-heating thepowder and post-heating the fused powder, being changed, for example,when modifying the one or more beam characteristics, during anyindividual pass of a scan pattern, and/or when starting or finishing anyindividual pass of the scan pattern.

In such processing, the post-heating of the fused powder can helpcontrol the cooldown rate of the fused powder, improving ductility,reducing residual stresses, and reducing the propensity for cracking atleast in portions of the fused powder. In contrast, a lack ofpost-heating effectively can quench the fused powder, increasing stressand improving hardness at least in portions of the fused powder. Thus,the manner and amount of post-heating can be tailored to influenceand/or control properties of the fused powder, in particular bymodifying the one or more beam characteristics to provide fine tuning ofthe post-heating effects.

In some examples, the method can further comprise: in additiveprocessing, alternately using the output beam to fuse powder and usingthe output beam to post-heat the fused powder.

As discussed above, in additive processing, it can be desirable topre-heat and/or post-heat the associated powder, as well as to fuse thepowder. In such processing, the output beam can be used to fuse thepowder, and also used to post-heat the fused powder. The output beam canbe alternated back and forth between fusing the powder and post-heatingthe fused powder, being changed, for example, when modifying the one ormore beam characteristics, during any individual pass of a scan pattern,and/or when starting or finishing any individual pass of the scanpattern.

In some examples, the method can further comprise: in additiveprocessing, alternately using the output beam to pre-heat powder priorto fusing the powder, using the output beam to fuse the powder, andusing the output beam to post-heat the fused powder.

As discussed above, in additive processing, it can be desirable topre-heat and/or post-heat the associated powder, as well as to fuse thepowder. The pre-heating can raise the temperature of the associatedpowder in a powder bed and/or an associated substrate above 100° C.,above 300° C. (e.g., lower temperature melt alloys), or above 600° C.(higher temperature melt alloys). As before, the higher temperaturesgenerally correlate with the processing of metals, while the lowertemperatures generally correlate with the processing of polymers.

In such processing, the output beam can be used to pre-heat powder priorto fusing the powder, to fuse the powder, and also used to post-heat thefused powder. The output beam can be alternated between pre-heating thepowder, fusing the powder, and post-heating the fused powder, beingchanged, for example, when modifying the one or more beamcharacteristics, during any individual pass of a scan pattern, and/orwhen starting or finishing any individual pass of the scan pattern.

In some examples, the method can further comprise: in additiveprocessing, using a first portion of the output beam to pre-heat powderprior to fusing the powder, and simultaneously using a second portion ofthe output beam to fuse the powder. In some examples, the method canfurther comprise: in additive processing, using a first portion of theoutput beam to fuse powder, and simultaneously using a second portion ofthe output beam to post-heat the fused powder. In some examples, themethod can further comprise: in additive processing, using a firstportion of the output beam to pre-heat powder prior to fusing thepowder, and simultaneously using the first portion of the output beam topost-heat the fused powder. In some examples, the method can furthercomprise: in additive processing, using a first portion of the outputbeam to pre-heat powder prior to fusing the powder, simultaneously usinga second portion of the output beam to fuse the powder, andsimultaneously using the first portion of the output beam to post-heatthe fused powder.

The variable BPP system as disclosed in this application can split theoptical beam into two or more portions. For example, the variable BPPsystem can split the optical beam into a relatively small, higher powerdensity central spot and a relatively large, lower power density ringsurrounding the central spot. In this case, as the optical beam passesover a powder bed, the surrounding ring can pre-heat the powder bed,then the central spot can fuse the powder, and finally the surroundingring can post-heat the fused powder.

In addition, the variable BPP system as disclosed in this applicationcan split the optical beam into other examples of two or more portions,as would be understood by a person having ordinary skill in the art.These other examples provide various combinations of pre-heating thepowder bed, fusing the powder, and/or post-heating the fused powder.

When splitting the optical beam into two or more portions, the modifyingof the one or more beam characteristics includes modifying one or morebeam characteristics of at least one of the two or more portions.

In some examples, a method of processing by controlling one or more beamcharacteristics of an optical beam can comprise: launching the opticalbeam into a first length of fiber having a first RIP; coupling theoptical beam from the first length of fiber into a second length offiber having a second RIP and two or more confinement regions; modifyingthe one or more beam characteristics of the optical beam in the firstlength of fiber, in the second length of fiber, or in the first andsecond lengths of fiber; confining the modified one or more beamcharacteristics of the optical beam within the two or more confinementregions of the second length of fiber; and/or generating an output beam,having the modified one or more beam characteristics of the opticalbeam, from the second length of fiber. The first RIP can be the same asthe second RIP.

Having described and illustrated the general and specific principles ofexamples of the presently disclosed technology, it should be apparentthat the examples may be modified in arrangement and detail withoutdeparting from such principles. We claim all modifications and variationcoming within the spirit and scope of the following claims.

1-20. (canceled)
 21. A method of fabricating an object, the methodcomprising: processing a powder bed or work piece with a laser in whichoptical power is delivered from the laser to the powder bed or workpiece via an optical fiber using beam characteristic variations carriedout in-fiber without the use of free space optics, wherein the opticalpower is delivered from the laser using a scan pattern including aplurality of individual passes and the processing includes: performingat least part of an individual pass of the plurality of individualpasses using a first output beam emitted from the optical fiber; afterperforming the at least part of the individual pass, modifying one ormore beam characteristics of an optical beam launched into the opticalfiber to generate a second output beam; and performing a next part ofthe individual pass or at least part of a next individual pass of theplurality of individual passes using the second output beam.
 22. Themethod of claim 21, further comprising using the first output beam topre-heat powder of the powder bed prior to fusing the powder and usingthe second output beam to fuse the powder.
 23. The method of claim 21,further comprising using the first output beam to pre-heat powder of thepowder bed prior to fusing the powder and using the output beam topost-heat the fused powder.
 24. The method of claim 21, furthercomprising using the first output beam to fuse powder of the powder bedand using the second output beam to post-heat the fused powder.
 25. Themethod of claim 21, further comprising: using the first output beam topre-heat powder of the powder bed prior to fusing the powder; using thesecond output beam to fuse the powder; and using the second output beamto post-heat the fused powder.
 26. The method of claim 21, furthercomprising: using a first portion of one of the output beams to pre-heatpowder of the powder bed prior to fusing the powder, and simultaneouslyusing a second portion of the same output beam to fuse the powder. 27.The method of claim 21, further comprising: using a first portion of oneof the output beams to fuse powder of the powder bed, and simultaneouslyusing a second portion of the same output beam to post-heat the fusedpowder.
 28. The method of claim 21, further comprising: using a firstportion of one of the output beams to pre-heat powder of the powder bedprior to fusing the powder, and simultaneously using the first portionof the same output beam to post-heat the fused powder.
 29. The method ofclaim 21, further comprising: using a first portion of one of the outputbeams to pre-heat powder of the powder bed prior to fusing the powder;simultaneously using a second portion of the same output beam to fusethe powder; and simultaneously using the first portion of the sameoutput beam to post-heat the fused powder.
 30. The method of claim 21,wherein fabricating the object comprises using one of the output beamsfor one or more of cladding, cutting, drilling, engraving, glazing,heat-treating, marking, patterning, roughening, smoothing, surfacetexturing, trepanning, or welding, or combinations thereof, one or moreparts of the object.
 31. An apparatus to fabricate an object from apowder bed or work piece, the apparatus comprising: a laser system inwhich optical power is delivered from the laser system to the powder bedor work piece via an optical fiber using beam characteristic variationscarried out in-fiber, the laser system comprising: a variable beamcharacteristic (VBC) fiber assembly to carry out the beamcharacteristics variations in-fiber, the VBC fiber assembly to generate,from an optical beam provided thereto, an adjusted beam having variablebeam characteristics, without the use of free-space optics; a free-spaceoptics assembly coupled to an output of the VBC fiber assembly, thefree-space optics assembly to perform one or more optical manipulationson the adjusted beam; and a process head coupled to an output of thefree-space optics assembly to receive the adjusted beam or an opticalbeam derived therefrom, the process head to deliver optical power fromthe laser system to the powder bed or workpiece using a scan patternincluding a plurality of individual passes.
 32. The apparatus of claim31, wherein the one or more optical manipulations change the variablebeam characteristics of the adjusted beam.
 33. The apparatus of claim32, wherein the one or more optical manipulations change a divergence,beam diameters, and/or spot size of the adjusted beam.
 34. The apparatusof claim 31, wherein the one or more optical manipulations preserve thevariable beam characteristics of the adjusted beam.
 35. The apparatus ofclaim 31, wherein the VBC fiber assembly generates the adjusted beamdifferently for one of the individual passes than another one or theindividual passes, or the VBC fiber assembly generates the adjusted beamdifferently for an initial part of the one of the individual passes thana subsequent part of the one of the individual passes.
 36. An apparatusfor fabricating an object, the apparatus comprising: a laser system toprocess a powder bed or work piece with a laser in which optical poweris delivered from the laser to the powder bed or work piece via anoptical fiber using beam characteristic variations carried out in-fiberwithout the use of free space optics, wherein the optical power isdelivered from the laser using a scan pattern including a plurality ofindividual passes and the laser system includes: means for performing atleast part of an individual pass of the plurality of individual passesusing a first output beam emitted from the optical fiber; means formodifying one or more beam characteristics of an optical beam launchedinto the optical fiber to generate a second output beam after performingthe at least part of the individual pass; and means for performing anext part of the individual pass or at least part of a next individualpass of the plurality of individual passes using the second output beam.37. The apparatus of claim 36, further comprising means for using thefirst output beam to pre-heat powder of the powder bed prior to fusingthe powder and means for using the second output beam to fuse thepowder.
 38. The apparatus of claim 36, further comprising means forusing the first output beam to pre-heat powder of the powder bed priorto fusing the powder and means for using the output beam to post-heatthe fused powder.
 39. The apparatus of claim 36, further comprisingmeans for using the first output beam to fuse powder of the powder bedand means for using the second output beam to post-heat the fusedpowder.
 40. The apparatus of claim 36, further comprising: means forusing the first output beam to pre-heat powder of the powder bed priorto fusing the powder; means for using the second output beam to fuse thepowder; and means for using the second output beam to post-heat thefused powder.